Nancy:
I don't think you are off course at all. In fact, I think you have made an observation which extremely astute and has gone missed/overlooked constantly. It took me the better part of 30 years to put together piece by piece what is wrong with me. I gave up long ago on trying to figure out what was causing all my health issues as I decided to live with it. I have a whole pile evidence that all points to the fact that I have dysotonaumia (POTS etc) and it is likely caused by a hiatal hernia. You are correct that the vagus nerve goes through exactly where a hiatal hernia is located. It is true about the acid reflux/vagus nerve interaction (which is often discussed)... however.. what is not often discussed... if at all... is the fact that having a hiatal hernia crowds that area and can literally irritate the vagus nerve directly (by crowding it, pressing on it). I came up with this theory in my own situation a few years ago and I ran it by a GI specialist MD. He told me that what I posited was very very possible but that he wasn't sure what anybody could do about it. I have been so depressed and dejected about my health for so long that I haven't picked the subject back up yet. I am however gaining mental motivation to do something about the entire situation. (POTS etc...) and I stumbled on your post here..... you are the first person who I have come across who has also guessed that this connection exists.
If you are interested I can run you through my bits of evidence and why I believe it is happening to me and it is the source of my issues.
Chris
