It might be Celiac, or perhaps gluten intolerance. I had the cramping and frequent BMs like you describe and it was relieved by a gluten free diet. I also discovered I have a casein (dairy protein) intolerance and that alleviated another batch of symptoms.

You can only get a CD diagnosis from a doctor after blood tests and endoscopy while still on a gluten containing diet. Many of us didn't believe negative results and tried the GF diet anyway, and had success. So I think you'll find a lot of people don't think the current "mainstream" doctor testing is really sufficiently identifying those with issues to gluten.

But if you're open to self-diagnosis you could try an elimination diet yourself and see if you get better. Since it can take up to a day or more for food intolerance symptoms to hit, you have to keep careful notes. Also, enterolab.com does stool lab testing for gluten sensitivity.

Sorry to hear about the pain. I well remember sitting on the toilet sobbing from the pain.

P.S. Never feel embarassed to discuss toileting things with celiacs. We spend a lot of time talking about these things and pondering the mysteries of the intestines.