Spotting five days after?

Savannah

I had unprotected sex last week before I started my period. A little during and right after it ended. I ended five days ago so the 19th an haven't had any problems. Except for today I had some brownish spotting. And I also had unprotected sex last night as well. My bf didn't cum but we double dipped. Should I worry? Should I take a plan b pill?