My dog does the same thing. The vet keeps putting him on antibiotics, but as soon as they are done he starts again. I gave my dog benadryl and spray him with 50/50 vinegar and water solution. It seems to help. My dog is a cockerpoo and he gets ear infections very easily. Nothing seemed to help it but equal parts of alcohol, white vinegar and water. Boy did that clear it up. He has not had a ear infection since.