No appetite and digestive problems

[sandcastles]

My son is nineteen years old and has had gerd for the last seven years.  It has gotten increasingly worse over the past two years.  For the last year he has been taking prevacid.  He currently weighs 275 lbs.  He was also diagnosed with shin splints in 2006.  This bothers him when we go for walks and therefore limits his exercise regimen.   For the last five days he has had no appetite.  This is quite unusual for him as he eats regularly. Before his lack of appetite he said that the only time the stomach acid goes away is when he has food in his stomach.  I have had him to several doctors and they have run numerous tests before the lack of appetite issue started.  What would cause him to have no desire to eat, but not necessarily be nauseous?  

[sandcastles]

He has been to our family dr countless times and to the gastroenterologist.  He had an x-ray with contrast to see his small bowel and a colonoscopy.  He has not had the EGD test done though.

[jennerfennerbenner]

what kind of dr. has he seen and what test shave been done?