What Does A Rash Behind Ears Indicate?

Hi, I had a patch of scab behind my ear that won t go away. It s been there for a couple of years now. I have tried cleaning it with alcohol, hydrogen peroxide & even tried triple antibiotic ointment but it always comes back. It itches & I do scratch it & peel it away sometimes until it bleeds. I have no idea where it came from & it s no where else on my body. What can I do to get rid of it or treat it?