I'm bleeding ?

So my ex bf and I had sex a couple days ago and he came inside of me I took a plan b pill in less than 20 mins that that happened. But lately I've been having constant cramps, and been a little nausea . Right now when I went to the bathroom to pee I wiped myself and I was BLEEDING! Not a lot for me to worry but I just think it's rare because I already got my period about a week ago. Do any of you if plan b has these side effects and the pill can cause me to bleed ? Please help.