Uti help?

So I thought I had a uti so I go to the doctor and get tested and put on some antibiotics. They call me two days later and say I don't have a uti but go ahead and finish the pills anyway.

The thing is it still hurts to pee and now my back hurts so bad I can't even sleep more then a couple hours at a time.

Any ideas what this could be? I have another appointment on Monday, but have no clue what to expect