Plan B

I recently had sex with my boyfriend and I am ovulating. We didn't use protection and we think he might have came in me. I took the morning after pill an hour later so I guess my question is how well does the morning after pill work? Should I be worried still even after taking it or am I okay? And will taking muscle relaxers at the same time do anything to the pill? ( I was recently in a car accident and was given the muscle relaxers for my muscle spasms. )