Hello,
It is good that the scan has come out clear for any kidney stones. Causes can be divided according to the affected organ
and they are
Kidney conditions (
infection, pyelonephritis, kidney stones, polycystic kidney disease), Bladder conditions (cystitis, bladder polyp, bladder tumor), Urethral conditions (Sexually transmitted diseases, urethral injury, vaginal inflammation), and certain bleeding disorders. It can be due to chronic UTI or vaginitis also.