I Have Not Had Sex In 2years Until The 5th

I have not had sex in 2years until the 5th of january this year. I finished my period on the1st of january, had unprotected sex on the 5th, took postinor 2 on the 6th and I have been bleeding black blood since 9th. Is this normal? What can I do to stop it and how long is it likely to go on for