I recommend putting vinager drops in his ear immediately! This kills the bacteria and is highly recommended by my veternarian.

I was taken back by your post because just last night at 2:30 am I was awakend by my Chihuahua with this same problem. I called my vet and he recommended this remedy. So far Taco has not cried once over his ear and has not picked at it nor is his head tilted to the side. I will be putting 2 more drops in his ear before bedtime tonight.