In 2007 I had two large anal abcesses that finally turned into fistulas and a diagnosis of crohns in the colon. Abcesses just don't form for no reason. More than likely you probably have the starting of crohns also.
After my diagnosis, GI told me that the only way to heal fistulas as large as I had was to go on remicade. I refused to supress my immune system, so I did a lot of resaerch and found the SCD diet. I followed this diet with fanatical dedeication and in 3 months, the first fistula was hrealed up. In another two months the other fistula was also healed up. That was 7 years ago and I have not had a symptom or problem from my crohns since.
This is not a simple diet to follow and take fanatical dedication for it to work, but it sure beats hard core drugs.
Read the book "breaking the vicious cycle" which goes into detail about the SCD diet.