Thanks for your query,based on the facts that you have posted it appears that you have frequent urination
and pain middle of the back.
This could be either due to Prostatitis
Please get your routine urine test and urine culture done to find out the organisms causing this infection and antibiotics to which they are sensitive to.
Please take broad spectrum antibiotics like Cefotaxime
along with urinary antiseptic like Nitrofurantoin
twice daily and urine alkaliser thrice daily.and later on switch on to appropriate antibiotics as per culture report.
Get the prescription of medicines from your family Physician.
Ensure to drink more water.To keep your urine dilute This will help to control dysuria