Help! Really bad stomach problems...?

I have really bad stomach problems and I have been to many doctors. I have gotten a colonoscopy, endoscopy, i have been to a G.I. doctor and everything. NO ONE CAN FIGURE THIS OUT. I do not have IBS. My symptoms are mucus in my stool and really bad lower stomach pain until the stool comes out. I also have a lot of gas. Please, I need some answers. I eat healthy too and I am not lactose intolerant. I also exercise daily. WHATS GOING ON WITH ME? i havent been able to work for a year because of this. Constantly going to the bathroom. Sometimes I dont even go at all.