Probably an allergin to the enviroment. Try asking your veterinarian about it. It is either that or he just has an infection.
he might be having ticks. have a look. ticks can be dangerous for dogs and for humans as well.
Posibly flies.My German Shepherd had flies biting his ears until my dad went to Petsmart and bought a can with a shepherd on the front cover. It's called "Flys-off".He applied it to my dog and it was like an insect repellent!They all stopped bitting.Mabye you should buy a can and see if your dog's ears heal.
If there are scabs in your dogs' ears, it can be caused from constant scratching. I'm surprised that you haven't already contacted your vet so they could run a culture test to find out the problem. Ear mites can be one cause of scratching.Take your dog to your vet and have them do a routine check of your dogs' ears. That's the first and proper step to help your dog's situation.
Most likely the dog is causing the scabs by scratching his ears constantly. If he scratches his ears more than normal, it could be due to many different reasons. One you can check for right away is the presence of fleas or ticks. If that's not the case, she could also have ear mites. A trip to the vet would be required. If the dog's ears are "smelly" too, it could be an ear infection. Dogs with floppy ears who love to play in the water or who don't get their ears properly dried after a bath can develop yeast infection on their ears. Infections are easy to treat with ear drops, but you do need to take the dog to the vet for a diagnosis and prescription. Whatever it is, don't waste time and take your dog to the vet ASAP. As it also happens with humans, illnesses are easier and less expensive to treat when they are caught earlier.