I have the same problem with my male and have had him on antibiotics but still comes back. Yeast infection is my best guess...have been cleaning his ears out and putting the iodine on feet and iodine wabs to clean ears. The iodine is suppose to be good for fungus and bacteria but think might have to go with fluconazole since it seems to be more internal. Cutting out the grain and anything with carbs in it..I think some issues could be also caused the shots we give them to keep them from getting parvo, rabies, and etc. I also think that a compromised immune system from too tight of breeding might cause issues; all guess work when it comes to this area.