The only reasonable thing to do at this point is to see a doctor. There are serious medical conditions that cause GI problems that won't be immediately impacted by diet. I have to wonder why this obvious next step isn't working for you. Can you see a doctor, with your insurance situation? If you can, then please do. Have you seen a doctor before for these issues, and was the experience not positive? If so, please don't give up, and try again.
Have you ever been told these could be psychosomatic issues? I don't want to carte blanche endorse the idea that this is a psychosomatic issue, because people with real medical issues have been discounted by doctors. However, if nothing seems to work in an extreme way, and there is no evidence of a medical problem, this is something to consider. Psychosomatic issues are linked to anxiety, and resolve through therapy and various forms of anxiety treatments.