Does sound like it could be IBS or even celiac. Did your dr's suggest either of those after other things were ruled out? IBS is usually dx after all other gastrointestinal diseases or problems have been ruled out. Celiac, you can get blood tests.. However the blood tests are not perfect and can either suggest you have it or not, there are false negatives, an endoscopy with biobsies of the small intestine can rule it out better than blood tests.

I know it's frustrating when the dr's come up empty handed. I've been tested for everything under the sun and will be starting my second round of gluten free diet shorty.