It sounds like he has Ear Mites. I would go to a Health Food store and see if they have Ear Drops with Grapefruit Seed Extract and Tea Tree Oil in it. It would be okay for a Dog. You could mix it up youself with water I guess, but I have no idea what the correct ratio would be.
Another thing would be to buy a Zapper and Zap your Dog, if you could hold him still long enough. This will get rid of the Ear Mites.