What do I take if I feel like I have a UTI but doc says no infection no stones?

I've been to the doctors they say I have no signs of infection and they say i have no stones that showed up in the ultra sound. But, I have ALL the symptoms its very uncomfortable. My doctor wrote a script for dicyclomine it didnt seem to work much. What about AZO I took it once and my back hurt really bad i'm thinking about take it again at a lower dose just because this sucks so much!