Food alergies

My 9 year cat has, what looks like mites in his ears and it smells, my vet tested it and said it is not. He must have a food algery. We feed dry food, what kind of food should we be using. Or what types of ingredients should we avoid?

I have been researching a lot lately about cat food. From what I've read, it appears as though you should avoid anything with "corn", "corn meal" and "by products". And, evidently you really get what you pay for in cat food. Cats are meat eaters and the dry food we feed them (and the canned) has basically "junk food" in it - causing all kinds of health issues.
   
I have posted a question myself about this topic.

What food has worked for you?