Need HELP Fast!!!!!!!!!!!!!!!!!!!?

my rottweiler has had bad ears for almost 2 years and shes only 3. its only the 1 ear but she scratches it till it looks horrible inside, (blood, scabs, etc.) and then she will go absolute mental for an hour ( scratching, panting, running round the house like a looney) and its so painfull for me to even watch. ive taken her to the vet on 3 occasions and have paid alot of money on various diffferent ear drops and they work for her within a few days shes fine but it keeps coming back, in the winter not as often a month or 2 and in the summer every 2 weeks to a month. do any of u have any experiences from your dogs or know anything that might help if so plz let me no.