I assume they've checked him for Crohn's? Other than that I'd have no clue. Hopefully he feels better soon, and they figure out what's wrong.
Gotta love blanket diagnosis like that, thank goodness they don't have many of them anymore. I was reading about hysteria and everything it covered 100+ years ago, nearly anything wrong with a woman.
My son had alot of blod wwork and had scopes done. All came back normal. That was before his surgery. Things haven't changed that much. A friend of mine is having problems with her daughter with stomach pains and the ER dr told her she is ovulating!
My friend had her gall bladder out in June and has been having similar problems. She has been to several doctors and they keep running different tests. She is scheduled for another one where they put the tube down your throat. I can't remember what it's called. I'm so sorry your son is going through this. Keep push1ing and go from dr. To dr. If you aren't getting the right answers. Best of luck.
Has your friend asked her doctor about bile reflux? My son has that now because of his lack of a gallbladder. His Gi doctor didn't look at that option, my friend told me to tell his doctor about bile reflux. He couldn't eat or drink anything without vomitting because of all the bile.