Get Your Dog Care Questions Answered by Experts
It sounds like he has an ear infection and you need to see the vet. There is nothing that you put in the ear until after you find out what the problem is. Using a product when you are unsure can cause deafness and more problems.
This could be a yeast problem or a bacterial problem. Using a yeast medication on a bacterial problem (and vice versa) will not help and it can actually do some damage.
The big thing to worry about with the ears is the head flapping. This can cause a blood vessel to burst in the ear and cause a hematoma. This requires surgery to repair. The last one that we had repaired was $280.
You need to get this taken care of soon so you can avoid the hematoma and get some relief for the dog.
Let me know if you have more questions.