Hi. Thanks for your query. Noted the history and understood the concerns. Irritation around anus for the last one week with a discolored ring like lesion and bumpy appearance with no history of anal sex indicate that you have dermatitis of the peri-anal skin. The causes can be: Infection of the colon causing the seepage of the infective material and causing dermatitis with changes in the skin around. Excessive sweating and covering of the area in underwear for so long can cause such changes in the skin. Possibility o pin worms can not be excluded unless you get the stool tests done. Also rule out diabetes by blood tests. I would advise you the following in such a situation: Clean the area with plain water, apply no soaps or any other chemical containing things. Make the area dry with a hair dryer. Apply Liquid povidone iodine twice daily and let it dry before putting on underwear. Avoid hot and humid atmosphere. This should be working well. Take medicines for pin worms. Antibiotic and metronidazole if there is an intestinal infection on test. Probiotics and multivitamins help a lot.