Itchy Ring-Shaped Rash

Marcus is a 21-year-old male presenting with itchy expanding ring-shaped rash on the forearm for 2 weeks. I'm a 21-year-old college wrestler and about two weeks ago I noticed a small itchy spot on my left forearm. It has slowly grown into a ring about the size of a coin — the middle has cleared up but the edge is red, scaly, slightly raised, and itchy. I wrestle and use the gym and locker room a lot and sometimes share towels with teammates; one of my teammates had something that looked like this. Your task is to take a focused history from this patient.