From what i can comprehend, i suggest you see a Urologist
. Get your urine r/e and culture and sensitivity done and use antibiotics according to that report. you also need to tell me if you have any injury
to your penis or surrounding area? how many times do you have to urinate? does it hurt to urinate? how is your stream? and the color of your urine?
it seems your physician is treating it for prostitis or UTI, and that too without a culture and sensitivity report. from the information you have given it is very difficult to conclude.
I wish you best of luck and take care of your self