Hello I share your concern. Injury or infection may occur due to tight anal sphincter and dry anal canal comparatively. Chances of infection are as such high with unprotected anal sex. In my opinion you should see general physician or dermatologist for physical examination and a battery of investigation to rule out Infection like blood for CBC, ESR, liver function test, VDRL test and urine culture test. You may require a course of antibiotics under medical supervision Meanwhile use antiseptic or antibacterial ointment to avoid superadded infection and keep it clean and moisturised Please write back to me with following details so that I will be able to tell you more precisely, like Since how long you are having this problem is there any history of discharge or oozing of blood if possible upload me a photograph. waiting for your reply. Best wishes