Suggest Treatment For UTI And Frequent Urination

My name is Bill. I am 48 and have a UTI according to the doctor i am seeing. He has put me on Tab interpharm or bactrim DS not sure how to read it. i have only had 2 doses. since taking it my condition seems worse. Meaning i feel like i have to urinate all the time and can't sleep. The tip of my penis burns or is very uncomfortable. I am drinking lots of water. Is there something else i can do? And how long does this part of the process take? I am on these pills for 30 days.