My Fiance, A 53 Year Old White Male Had A

My fiance, a 53 year old white male had a mild rash on his inner thigh. He developed this the day after swimming in a lake. The rash spread to his groin and has become just raw skin. He has tried ointment and medicated powder but it has only gotten worse and spread. There are no bumps, only raw skin. Due to his work schedule, he cannot get to the doctor until later this week. Do u have any suggestions of products to use until he can get to a doctor?