Spanky the cat

My bf and I just adopted a cat from a local animal shelter and we have noticed something wrong with his ears. After a few days we noticed that he had a bald spot on one of his ears. We took him to a vet for a check up, and she said that if the ear starts to scab that he might have something. Well it started to peel, and now it looks like it may be scabbing up. Also, the other ear has started to bleed at the back. Any ideas on what it might be?