You should be fine as far as pregnancy. Plan B can sometimes mess with your period so if it comes early or a little late don't be too worried. And try not to stress because that can sometimes cause your period to be late.
Thanks. I got the plan b pill within tbe first 24 hours after i had unprotected sex. my period is due this coming tuesday.
Usually brown blood is old blood. It could be that you got a small tear during sex. If you're going to take Plan B then you really need to get it as soon as possible. They say to use it within 72 hours of unprotected sex. The sooner the better though.