Per-anal itching. And very distracting.

Have had this issue for 2 years. Colonoscopy done 3 times. First time diagnosed as anal ulcers. Second time as some infection. Third time as granuloma. Biopsy was taken first and third time. Nothing specific found in either biopsy. Doctors ruled out any worms. Only some kind of ulcers located at a finger length inside from the anal opening. There is no bleeding but the doctors found some pus. Suggested treatment was local application of some ointments like Anovate, Shield, Socralcoat, etc. They work from time to time but then sometimes peri-anal itching becomes very uncomfortable. No permanent solution found by any of the doctors i have referred and i have been to 3 different reputable hospitals. Most of them say to ignore it and put it out of mind.The problem had reduced quite a bit last year but then i had thrombosed-piles for which i had a surgery, stapled hemorrhoid-ectomy after which the issue came back and the itching due to the ulcers/granuloma is worse and very distracting.