Abdominal Pain. Diagnosis possible?

I get varying levels of abdominal pain whenever I do any kind of exercise (walking, playing, gym). This problem has been present in some form for 3 months. It starts out very mild but gets more intense if I continue doing anything. Subsides when I get back to bed and rest for a while. I have been to a physician, he wrote a sonography and urine test, both came out normal. After the problem persisting he did an endoscopy today and it came out normal as well. No ulcers. He doesn't have much clue as to the cause of the problem now and thinks its because of intestinal pulsation being misconstrued as pain. Has currently written prescription for cyclopam and Rablet. Any other diagnosis possible? Any help is appreciated. This problem is getting worse. And I am starting to get seriously worried about this.