I Have A Reoccurring Bladder Infection, More So Since My

I have a reoccurring bladder infection, more so since my hysterectomy almost three years ago. I get them several times a year, but lately I haven't been able to get rid of it. I've gone to the clinic three times since December. Always on Cipro which normally works. This time, I'm on Bactrim and its been 3 full days. And this time, a low grade fever and lower back pain, which concerns me. The NP told me to go to my PCP when the antibiotics are all taken for further testing, maybe it's in my kidneys. The pain is still there when I urinate so I'm taking the prescription peridium. Should I just keep with my current plan or should I be doing something else, more tests?