Wht could cause a two days bleeding after 5wks of unsafe sex? postinor 2 was taken on the 2nd day after sex these led to 5days bleeding on the 3rd day

It happens sometimes: Plan B, Postinor 2, and other brands of emergency contraceptive pills can alter the menstrual cycle vaginal bleeding for the cycle in which Plan B or Postinor 2 was taken, and sometimes the next month's cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because emergency contraceptive pills work most of the time, but not all the time.