Anyone here on pembrolizumab immunotherapy and suffering with a really sore bum? My DH is nearing the end of a 2 year course and every time after treatment he gets a terribly painful sensitive rectum for 7-14 days. The doctors say there is nothing to see, it's not a fissure or piles or anything like that, it's just awfully sore. The best thing he has found is Sudocrem, and using lactulose to keep everything going through soft, but I wondered if anyone else had this problem and if so, what you use to help. TIA.