It seems like Chris has a perpetual ear infection due to his overabundance of ear pollyps. It was in both ears but now it is only in his left ear. I got a different medicine from the vet and have been putting it in his ear pretty regularly but we have been inconsistent when it comes to cleaning his ears. Perhaps because putting in the medicine is easy but cleaning his ears involves a lot of struggling and frustration. Fortunately, Floki has taken over the ear cleaning duties and he does a great job with far less struggling from Chris.
Floki even knows it is his left ear that needs cleaning.