Hey, back here to talk about my experience.
I have been "officially" diagnosed with neurocardiogenic syncope and dysautonomia, and "unofficially" with POTS. POTS/neurocardiogenic syncope are related, anyway.
Whew, where to begin. Basically, I got really sick about a year ago with major GI symptoms. Nausea, vomiting, no appetite, abdominal pain. I ended up having my gallbladder out, but my issues continued. I was diagnosed with gastroparesis and severe functional constipation - basically, a test showed that all parts of my GI tract work way too slowly. I have been treated medically for this with different medications, and I'm doing okay.
But I have had another set of symptoms related to my blood pressure. For years, I have felt woozy, lightheaded, pounding palpitations, and my vision blacking or graying out often when I stand up from laying or sitting down. These symptoms got a lot worse in the past year. My primary care dr noticed that I had orthostatic hypotension in her office. My BP dropped about 15 points from sitting to standing.
I started seeing a new GI doctor who is a real researcher. I happened to mention my low BP symptoms to him. He is the first person who suggested the diagnosis of dysautonomia to me. Basically, it is when your automatic nervous system, which controls functions like blood pressure, digestion, bladder and bowel issues, etc. malfunctions. He said he thinks my GI symptoms/gastroparesis are related to a larger autonomic dysfunction.
My GI sent me to have a tilt table test to "formally" diagnose me. I "failed" the tilt table test (or it was "positive", I guess). For this test, you are strapped on a table laying flat, and then tilted up to a standing position. You "stand" there for a certain amount of time (20-30 mins, maybe). My BP dropped and my heartrate increased upon standing, but then adjusted. But after about 15 minutes, I experienced "neurocardiogenic syncope" - my blood pressure bottomed out to 50/20, my heart rate went way down, and I passed out.
Anyway, the result of all this is that now I'm being treated for this dysautonomia. I am about to start 2 new meds. One is midodrine, which is to increase BP. One is an SSRI antidepressant, Celexa. The SSRI sounds crazy, but apparently it has been used successfully to treat dysautonomia. It has something to do with the serotonin receptors in the brain.
I'm a bit nervous about starting new meds, but I guess it's worth a try. My GI and cardiologist both seem to think after 3-6 months of therapy, I may be able to go off the meds and still have improvement.
It really sucks though! I have felt bad for a long time and it's tough. I think this syndrome is common in adolescents and children, and they have better chances to spontaneously recover. I'm 27, for what it's worth.
Good luck to your son!
Edited to add: I'm also supposed to really push fluids and salt.