It sounds like a chronic ear infection. Most of time I will do a culture and sensitivity test to find out what kind of germ and what is the right antibiotic to take care of that. And I will do a thorough ear flush under general anesthesia. Otherwise the topical medicine won't go in well. For the chronic otitis, it may take a long long time to recover. If the problem is too severe, some time we will recommend to do a Zap procedure(to open the ear canal surgically) or even a total ear ablation.
Hi:
I am sorry for the late response. I didn't notice your question earlier. I think the the key point is the sensitivity test to find out which antibiotis really works on the germ. The creatinine values you gave me are all within normal range. Don't worry too much. Please let the dog have free choice of water all the time.