I was looking at Misty's ears today and saw that he had little dark brownish spots scattered in the inner portion of both of his ears. I then looked at Marbles' ears. She didn't have any. Does Misty have ear mites or something? Please tell me!!
It sounds like ear mites to me. Are the brown spots sort of waxy, and easily removed with a q-tip (don't stick the q-tip in her ear, though!)? The vet can clean out her ears properly and give BOTH cats medicine for the ear mites, as well as see them to know if that's for sure what it is. If one cat in your house has it, they both probably do.