Ear mites are only one cause of ear infections in dogs. Yeast and bacterial ear infections are more common causes of head shaking in dogs especially if the ears have already been treated with an insecticide as you have already used. His ears should be checked by a vet and a cytology should be performed on the ear discharge to determine the cause of the infection.
A cytology is performed by placing the ear discharge on a microscopic slide, staining the slide than looking under the microscope. Ear mites, yeast, and bacteria are all visible under microscopic illumination. This can be performed during the office visit. Your dog may need another medication such as: Otomax, Mometamax, or Tresaderm with a bit of additional anti-fungal added.
Thank you Dr. Cheng, I have only had this animal a short time, hence the no Vet visit as yet. Now after a short discussion with his(Jack's) previous owner; my findings are as follows; 1) he's never been to a vet.
2) Jack hasn't had any shots:(parvo, distemper, & rabies)
3) His "ear distress" may not be predetermined from my suspicions only.
So I am taking him to Hardy Richards DVM, ( here in Kenedy, Tx) and getting him a good looksie! Thank you Dr. Cheng again; I'm familiar with cytology because I once did lab-work. I loved it but the oil field beckoned me to make more$$. Have a great day, I know Jack's condition should only improve with treatment and the kindness that people like you share with us pet-lovers. You have done wonders with human stress as well as Jack's "problems". I can't believe his previous master was so negligent. James