What Causes Severe Abdominal Pain In A Teenager?

Question : My son (14 years old) has severe abdominal pain - almost constantly, day and night. It has kept him out of school for 9 weeks now. He has burning pain, but also achy pain - not appendicitis. Pain is in central belly around belly button. He tested negative for celiac; has no blood; cal protective (sp?) is negative, so Crohn's, ulcerative colitis, and diverticulitis are not likely. Not losing much weight. He was scoped last spring (he had same problem then and after a few months - and we took him off of Concerta - the problems subsided) and they only found a slight abnormality with the esonophiles (sp?) so he has slight GERD. He had a lactose test - very slight lactose response - but barely. He had an MRI - nothing. Tested for parasites - nothing. Was off of gluten and dairy for about 3 weeks - no improvement. I just got a call that the plumber will be here early - in 20 minutes

I forgot to write that my son has started Nexium 22.5 mg, 2ce/day, and amitryptalene at night, and sucralfate as needed. So far, I have not received any emails to my first question sent 54 minutes ago.

In the original message, I meant to write, "he has no blood in his stools", instead of, "he has no blood". I was interrupted while writing and forgot to finish the thought. The doctor (Pediatric GI) thinks that it is a "brain-gut" problem, meaning that his brain is firing signals for pain for no real reason. They also are recommending biofeedback. He had ultrasound of the abdomen back in March. He had endoscopy in April. They told me if he had had a peptic ulcer, and even if it had healed by the time of the endoscopy, months later, they still would have seen remnants of it.