You might try getting a product called Yeast Buster from America's Bio-Plus 
Corp.  After 6 months of recurring yeast infections, I read an article in Whole 
Dog Journal written by a woman who cured herself and her dog of yeast 
infections (which is usually the cause of ear infections in dogs) with this 
product.  I bought some and have not had another infection since!  By the way, 
my dogs drink CS water and never have ear infections.