Here is a good site to start with:
http://dysautonomiainternational.org/index.php
I'd recommend that he see either a cardiac electrophysiologist or a neurologist who specializes in dysautonomia. The link above has maps od doctor's locations throughout the world. I would start there!
I suffer from vasovagal syncope as well. My first episode was in May of 2012 and I just got an answer to my problem 2 months ago! I saw an electrophysiologist who performed a tilt table test and diagnosed me with postural orthostatic tachycardia syndrome (POTS). POTS is what causes my vasovagul syncope.. Hope that helps and good luck
I suffer from this, cut out all diuretics including coffee, drink water and Gatorade, the full sugar one, salt+sugar increases absorption, proven in countries with drought..likely an electrolyte imbalance...blood flows on water...I had 2 saline water bags added in me in the emergency room..felt instantly better for months. It's a problem with not retaining enough fluids. Water alone is not enough during extreme cases. May be triggered by heartburn too. Don't overfill your stomach.
The responses above are all good, he also can try compression stockings, recommended to us by a physician, my wife has similar trouble. There are meds, next step (we are not there yet), change docs if you get no help. An endocrinologist or internist (internist with experience with Addison's disease was helpful to us). Good luck!
I'm sorry your husband is having so much difficulty finding an appropriate treatment. I would recommend seeking a Cardiologist in an Academic Teaching Hospital for further testing and treatment. Has he ever had a Tilt Table Test?
Diagnosing Dysautonomia:
http://www.medhelp.org/health_pages/Neurological-Disorders/Diagnosing-Dysautonomia/show/827?cid=196
Dysautonomia Specialists:
http://www.medhelp.org/health_pages/Neurological-Disorders/Dysautonomia-Specialists/show/717?cid=196
I do not know where you are located but my advise would be to find an autonomic lab and have your husband tested. There are not that many facilities in the US, so you will probably have to travel. Vasovagal Syncope is one of the milder forms of Dysautonomia and there are medications that can help greatly. When he was diagnosed did they prescribe any medications for him to try?
My husband suffers from same thing....we went to an endocrinoligist, where husband adrenal function was ok, but was given fludrocortisone to keep his BP from falling out, and it has helped dramaticially with the syncope episodes. Since then he has also been evaluated at Cleveland Clinic, OHIO...at their SYNCOPE CLINIC....see if there is such a clinic near you. By the testing they did, it showed his autonomic nervous system...anything your body (nervous system does AUTOMATICALLY...regulate BP, heart rate...things you do not think about to do..) does not work while he is standing. It is a cardiovascular doctor that does this testing normally. NOT JUST TILT table testing, as that was not helpful for us. Hope this gives you some insight. M