I would defintely ask the vet to do a culture before he gives you any more antibiotics. Our Dalmatian got frequent ear infection, treated him with antibx, repeated. Finally a culture showed it was a yeast infection in his ears. The treatment: (are you ready?) Monistat vaginal yeast cream!! Yep, got it at Walmart and used it in his ears for 7 days and they cleared right up. Don't use this unless you get it cultured but it's worth mentioning to your vet. Good luck!