Was it spotting from taking Plan B or was it my period?

I had sex and he came twice and on the 2nd time he pulled out and the condom was halfway off. To be safe I took a plan b one step that same night. 5 days after taking it I began to have brown discharge that progressed into heavy, red blood with blood clots in it that lasted 5 days much like my period except I wasn’t due for my period for another 12 days. I am not at the point where I should get my period for this month but I’m confused as to if that was my period? Please help, I know plan b should have worked since I took it within 24 hours but I am trying to figure out whether I should worry or not.