It sounds like the vet was treating it as a fungus. The tinactin works for yeast infections so it might work on this as well. But you have to keep the dog from licking it. This is hard to do around the feet.
The best way is to slide a baby or child's sock over the foot and tape it loosely at the ankle. This will limit his access and give it time to heal.
Let me know if you still have questions.
