I am sorry you are having so many issues going on. Its never fun when our bodies rebel against us! There are different doctors who treat dysautonomia but from the sounds of what you are experiencing you may want to see a neurologist and an endocrinologist. I found that learning about my disease and diseases in general which could be causing symptoms helped me learn about and eliminate other things when i didn't know what i had via online research. Also, when these events happen, keep a journal with dates and times of what you are feeling and try to describe it the best you can--talk about what it is you are feeling. When these episodes happen, use a thermometer to take your temperature, and check your pulse--count it for 60 seconds and that is your heart rate. Record that data in your journal. Normal resting heart rates can range from 55-80 beats per minute depending on your fitness level. You can also buy a blood pressure cuff online if you would like and record those values during episodes as well. When these episodes happen try taking your heartrate and/or blood pressure with changes in position: lay down for a couple of minutes, then take your pulse for 60 seconds and record it. Then stand up and take your pulse. If the pulse raises past 30 beats per minute and stays there or if your blood pressure drops by 30 mmhg that can be a tell tale sign of dysautonomia that you should inform your doctor about. If they are normal thats a good thing, one less thing that could possibly be wrong. As for your symptoms, it sometimes helps to understand how the body works to understand what may be causing your problems. From what i read it sounds like your chief complaints are nausea/confirmed gastroparesis, episodes of hot burning skin sensations, weakness, buzzing sensations in your ears, low blood sugar, dizziness, pcos, at least one confirmed indcident of low cortisol, and sometimes diarrhea. When you go to a doctor, that is the list of symptoms you should present them with. So, as far as understanding your body mechanisms i will go through them one at a time. Nausea is very non specific, there are a lot of things that can cause it. In fact having a low am cortisol level can cause nausea. Having gastroparesis could probably cause it as well. If they have looked at your gi tract and not found anything other than gastroparesis its possible that what you are experiencing is not originating from your gi tract. On that same note however, a full workup of the gi tract would include much more than just a barium test. It could include a colonoscopy, checking your pancreas both through imaging and also its enzymes, checking fecal occult for blood, checking for intestinal parisites, checking your liver enzymes, checking for gluten sensitivity, and also checking for lactose intolerance--these tests can help to eliminate the gi tract as a primary cause for your symptoms and in my opinion, its important that you do that to rule out a gi origin. It is possible that all these things you are experiencing are related and its also possible that you are experiencing different symptoms from different and separate causes. Once the gi tract has been ruled out you can begin to look other places. If the gi tract is not the cause of nausea, it could be your cortisol levels, your thyroid levels (tsh, p3, p4), other hormones, a brain abnormality, dysautonomia, a tumor somewhere its not supposed to be, anorexia/bulemia, anxiety, heart abnormalities, seizures, a viral or bacterial infection, drug withdrawl, and/or a variety of other things. This is why it is so hard to find a specific cause for nausea--it can come from many different places. As far as treating nausea itself, the drug zofram works wonders in my experience.
The hot burning skin sensations can be caused by a few things. The first is neuropathy. This is when the nerves in our bodies become damaged either by an autoimmune process(ehlers danlos syndrome, marphan syndrome, lymes disease etc) injury, or poisons such as sugar (diabetes), alcoholism, heavy metal(such as lead), or other toxins. That damage to the nerves can cause a burning and hot feeling and if the nerves to the gi tract are damaged, can also cause gastroparesis. Neuropathy is diagnosed by a neurologist. They do what is called a QSART test and also a nerve conduction test. These tests detect abnormalities in the nerves themselves.
If the burning and hot sensation is not caused by a nerve abnormality, it could be caused by your blood vessels overdilating. When the blood vessels dilate they open up. This causes a release of heat and water molecules leak from the blood vessels into the skin causing us to sweat. So if we are sweating--they are dilated. Things that can cause this are blood vessel abnormalities, hormones--especially adrenaline, dysautonomia, pots, anxiety, and also neuropathy.
When we we experience fear(whether real or imagined) or have a death threat to our bodies either from an external source (car accident, lion chasing you, etc) or an internal source that prevents glucose and oxygen from reaching our brains ( heart attack/problem, bleeding to death, low blood pressure, low heartrate, low blood sugar, starvation, lung collapse etc) it causes our bodies to release adrenaline to try and survive in those situations. Adrenaline changes how our blood vessels are dilated and also how forcefully our heart beats--the beats become stronger. It causes massive amounts of glucose to be released to the muscles(so that we can run away from the lion or lift something heavy that may have fallen on us) and this causes the muscles to shake. It also increases how quickly we breathe to deliver more oxygen to the brain making us hyperventilate. It can also make us very nauseous which is why some people throw up after a stressful incident. Your incident in the bathroom could have been caused by adrenaline release. These can definitely be caused by dysautonomia, but could also be caused by anxiety(through the vagus nerve), or many other things. I know adrenaline rushes can be very scary, especially when you dont know why they are happening and it feels awful--but just remember, your body is doing exactly what its supposed to do to help you survive--thanks body!!
The buzzing sensation in your ears could be caused by a problem with your ear, or it could be a sign of a seizure, nerve damage, an anomoly, heavy metal posioning, malnutrition, or dysautonomia. I have POTS and my ears ring and the sound goes in and out quite often. I have also read about a lot of people with dysautonomia who do get buzzing but I have never experienced it first hand. Neurologists test for seizures by doing what is called an EEG and that may be a test you consider doing as well.
As far as the hormonal imbalances go, those levels are regulated in various parts of the body. They begin in the brain in the hypothalamus which is also a major player in adrenaline responses. The hypothalamus oversees all of the hormonal and autonomic responses for the body and is located in the back of the head by the brain stem just above where your head meets your neck. From there, they hit the pituitary gland which is next to the hypothalamus in the brain. From the pituitary gland those hormones can go many different places such as the adrenal glands on top of the kidneys--to release adrenaline--, the thryoid which is in your neck, and various other places. Since you are having so many weird symptoms and hormonal imbalances a brain mri may not be a bad idea to make sure those things are in good working order and that you dont have a tumor, congenital(birth) defect, or something called a chiari malformation. This is where the brainstem gets compressed due to a birth defect and can cause all sorts of autonomic and hormonal problems.
At the end of the day, there could be many things that are causing your issues and for me, i had all of those things checked. If i were experiencing those things, based on what I know, my guesses would be hormonal problems, neuropathy, autoimmune disease, seizure, anxiety, chiari malformation, or dysautonomia. I hope that helps and that you are able to find some relief. Sending lots of positive vibes!