A few weeks ago we took Pepper to the vet because she had a lot of gunk in her ear. The doctor gave us some medicine and some cleaner to put in her ear. We used everything as directed and then took her back to the vet for a follow up. They said she looked fine. Now it's coming back, though. The other night I noticed her shaking her head a lot so I looked at her ear and there was a TON of runny brown stuff in it. I gently got it out with a q-tip then used the cleaner and some of the drops we had left. I've been using it ever since. I just don't understand why it won't go away. What causes this?