How Can UTI Along With Backache Be Treated?

Recently treated for a UTI. Still taking AMOX-CLAV. Just took my 6th of 10 doses of an 875 mg. The Doctor I saw, said my urine had an extremely high white blood cell count. I told him I had a dull pain in my side, and he stated the infection was probably making its way up my urethra. He eliminated appendicitis, because I could jump up and down. Still have this dull pain in my back that runs to the front. Any thoughts?