HI XXXXXXXX,
If there is a black discharge then it may be ear mites and for that you would need medication to kill the mites as they can spread to other parts of the body and other animals . I understand that the dog had problems the last time the vet worked on the ears and if you mention the problems he had and that you don't want him to take certain meds . Prednisone should not be needed for ear mites. Here is more on the treatment of ear mites. http://www.petplace.com/dogs/ear-mites-in-dogs/page4.aspx
dog training consultant
24 years training & behavior,pet first aide, Therapy dog eval., PA Animal Response Team