Infections, especially those involving the pelvic region, cause menstrual disturbances. The type of the spotting you are experiencing is suggestive of breakthrough bleeding
. This is likely to have happened due to the urinary infection you have suffered from. It is also likely that the hormone status is disturbed as a result of the infection. Please get proper evaluation by a specialist to plan further management. This cycle may not be protected. You will need styptics, hormone supplements and proper treatment for the infection. Hope this helps.