Hi.. I know this post is a year old.. But I'm a 48 year old female who was just diagnosed with pots like a week or two ago after having a bad kidney infection and surgery and I have the exact same symptoms.. the shortness of breath ..fatigue.. racing heart... twitching muscles and I'm kind of a geek, so I do a lot of research looking at scientific papers... I do have a degree in medical billing and medical coding so I can understand about half of these scientific research papers LOL and I found an interesting article about mitochondrial cytopathies... it's a disease and it mostly strikes people in childhood but it does strike a lot of adults and it's usually a little less severe when it strikes in adults and it usually flares up at times of stress and a lot of the symptoms people are talking about on this forum like the drooping eyelids, the shortness of breath, fatigue constipation or diarrhea .... just a whole host of General symptoms and I'm not talking about being winded I'm talking about air hunger and a whole host of other symptoms that are actually symptoms that can go with this condition. I'm not sure how to go about getting tested for this I think it's a geneticist that would do this because it's actually like a strand of your DNA or your rdna that's missing at a certain place in your body which would give you whatever symptom you get... but it's interesting and worth looking into it if you feel like it. I think I did read that vitamin B12 can help some people if it was an adult onset and if that's the condition.. also it never hurts to be tested to see if you have vitamin deficiency...