I have been on microgestin birth control for 5 months and have had no previous problems. I take my pill every night on time. This month I had light bleeding for 3 days, only 2 weeks into the pack. Then that stopped and I started having to urinate more often as well as a burning sensation while I have been urinating. I had unprotected sex once and took the plan B pill. What could this be? I also had a very light pink color when I wiped after sex once while this has beenso going on, but did not reoccur afterwards. What could this be? A UTI?