After a year of ear problems off an on, using drops, antibiotic, anti fungal, earwash, etc. we started putting a dollup of yogurt in our Lab's food each day. Cleared his ears up within a week and no problems since.!
Time to see a vet. It could be a bacterial or fungal infection, and you need to be sure exactly what it is in order to treat it correctly. Poor guy - he's got to be just miserable.