Yeahhh. If you've got endo on your bowels, it is very common for it to cause constipation or diarrhea, bloating and gas. All sorts of GIT upset.
I have stage III endo, with the worst of it being down the bottom of my bowels, and I get the WORST gas, very painful, and a lot of it. I've tried changing my diet heaps, I've even had a colonoscopy and 2 gastrocopies. My gyno almost laughed when I told him I had those procedures, he said it's definately my endo.