Hello dear I understand your concern Plan b pill is 95 percent effective in preventing the pregnancy. So chance of pregnancy is 1-5 %. Plan b pill contain high progesterone and it cause dilatation of smooth muscle of the urinary tract and cause symptoms of urinary tract infection. Infection should be confirmed by urine routine and microscopic test. Take following advises: Tablet nitrozolium Tablet pyridium Syrup cital If not responds then take antibiotic septran. Antibiotic does not affect the effectiveness of plan B Do not delay in empty the bladder and empty the bladder completely Plan B pill itself cause delay in period by 8-10 days. SO if period will delay by the 12-14 days then go for pregnancy test. If pregnancy will detect then still you can terminate the pregnancy by abortion pill under the advice of gynecologist Hope this may help you Best regards Dr. Sagar