Started off as a UTI

Had a uti, went to doctor and they prescribed me cephalexin, which helped.... but I got a sharp lower back pain and I’m getting anxiety about it being an infection or even worse...:a failure, I’ve never had bladder/kidney problems before I’m super scared 

Irs probably nothing.  Just relax and breath!!!! I’m sure it’s fine.   

Have you any other symptoms?  Did your doctor take a sample and get a culture made?  Cephalexin is a strong antibiotic, usually only given if the first antibiotic doesn't work, so an unusual choice which is why I asked about a culture. 

Have you taken probiotics to replace the friendly bugs in your gut?