Do I have leaky gut, SIBO, food allergy or something else?

I am a 40 year old female with a history of colon cancer. Ten years ago, I had a colon resection which removed about one third of my large intestine. After the colon resection and removal of the cancerous polyp, I had few GI  or other health problems. For the past three years I have experienced extreme bloating, gas, fatty stools, many episodes of diarrhea after eating (where the colon seems to empty completely), joint pain, many sinus infections, fluid in the sinuses and ears (constantly present) loss of appetite, and insomnia. (I don't know if these symptoms are related or not but I thought I"d give the entire spectrum of problems.) My CEA level has been slowly creeping up over the years however, my CT scans, colonoscopy, pelvic exam, pap smear and pelvic/ vaginal ultrasounds, and recently a  hydrogen breath test (using "straight glucose" as the technician told me) come out clear. The GI I am seeing now (we have moved  several states away from my GI that found the cancer) dismisses my symptoms and says it must be IBS. He also says that food allergies would not elevate cea and that yeast overgrowth or other overgrowth would be detected through the breath test.Are there other diagnoses that would explain these symptoms and the rising CEA levels?