So I've always had stomach problems: too much acid, constant hunger, hungry but don't feel like eating, throwing up only at night, can't keep down nyquil when I'm sick, throwing up only acid, throwing up only grease, the list goes on..

I have gone through an ultrasound, several blood tests, and an upper GI series (drink barium then they take xrays of your digestive system), and the doctors have never been able to find anything.

Could this be caused by anxiety? The major problems only seem to come on whenever I'm extremely stressed about things like school, family problems, or just really really worried about an event coming up.

Any insight?