I just finished antibiotics for uti and i am having mid back pain. no fever or painful urinating. just peeing a lot. can this be kidney infection?

Culture?: If you have urinary frequency, I would go immediately to your doctor and give another urine sample. If there were culture results from your UTI, they are used to direct treatment. If you had a complicated UTI with flank tenderness/fever/chills the treatment should be longer in duration and involve a dose of IV or IM Ceftriaxone in my opinion. You should also have had a full STI panel. See MD