There may be some pathology anywhere
in the urinary
system from the kidneys,urters ,urinary bladder and urethra.It
is not compulasory that you are having an infection of the urinary system.It may be due to some other pathology like some obstruction.I would suggest you get a urine culture and ultrasound and CT pelvis done so that the exact cause can be determined.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional queries.Kind regards.