Treating your cat with topicals for ear mites works best. Especially if the cat goes outside. The one we use that works well is called Revolution. It's a once a month topical that goes on the back of the head, usually after two treatments (to break the life cycle of the mite which is difficult) your usually good to go. Working at a clinic makes it hard for me not to bring all the stray cats home with me. Right now I have four cats. Bucket, Paton, Rasputin, and Enoch. I'm responsible for Buckets name.. (I had fish tanks in Germany and he wouldn't stay out of the cleaning buckets and rocks...) and also for Raspy. None of the other cats liked him when he was a kitten... He was kind of a loaner and a little twisted thing.
My cat used to be a stray. When I was a kid, my mom was the manager of this place and found the kitten hanging outside. She got me to come over for it, and I brought the cat home, and she's been my baby ever since.
That sucks. But I know people who love cats yet are allegic, and were able to get allergy shots that got rid of the symptoms. Not sure if that's an option or not for you?