Possible pregnant?

I had my period about 10 days ago.. I had unprotected sex 2 days after I got off my period and he came in me. I took plan B the next day. I started my period again today, I looked up online and it said that plan B can cause you to have your period earlier than usual? But at the same time I'm scared this means I'm pregnant because some women spot in the beginning of their pregnancies.. Help!!!!