I have been bothered by some kind of rash behind my left knee, and on top of my left leg for about 3 months. It started as a sore behind my knee, that was open, and I thought it was an insect bite. My doctor, and my daughter (a pharmacist) thought it was Impetago, and I was prescribed Mupirocin ointment. I have been using it for 3 weeks, and occasionally wash with soap and water, and the apply Gold Bond Medicated powder.