Pain in ascending colon (2 weeks now) while sitting, not standing or walking; doc says its due to stress, i got gerd as per his earlier check up?

See below: Symptoms and concerns like these mandate a thorough evaluation by your doctor. Only after such an evaluation, which may include labs and radiographic examinations, can he/she let you know what's going on and how best to help you.

Positional: It sounds like the pain is more positional rather than stress related. It might be time for a second opinion and an evaluation like dr. Sparacino recommended. With a history of GI problems, as you indicated, it's probably time to see a gastroenterologist.