Crohn's is under control, but what could be causing bleeding from rectum for four months after perianal abscess surgery? 5 drs visits-no advice.

Fistula. You may have a perianal fistula or other anorectal problem that is causing bleeding. Typically this would involve examining the inside of the colon with some form of endoscopy and an exam under anesthesia to diagnose the problem.
Crohn's. Unfortunately, crohn's disease frequently involves very severe and atypical problems in the perianal area, including chronic fistulas. While the disease may be controlled overall, patients with anal fistulas may suffer prolonged symptoms, and are quite difficult to resolve.
Rectal bleeding. Find colorectal surgeon. Dr. John marks in philadelphia area at lankenau hospital is a good choice. Unclear where is your location. Rectal bleeding can be caused by hemorrhoids , cancer, polyp, injury among other causes.