I would ask the doctor to perform a colonoscopy of the colon. My blood work and fecal tests proved zero, but the colonoscopy told a different story. You will need a gasternologist usually to do this as they should be more familiar with the procedure. You will go in as an outpatient and will be out for most of it. It wasn't that uncomfortable so good luck. I have Trigon Blue Cross so almost all of it was paid for. It used to be very expensive but doctors have lowered the price to under $2,000 for the procedure.Good luck.