Does Next Choice Pill Affect Menstrual Cycle?

I took the next choice pill within 24 hours of having unprotected sex with my husband. The very next day i started spotting that lasted for a week or so. I have been cramping but I still haven't gotten my period and im about 2 or 3 days late. My question is could I be pregnant and does the next choice pill affect your menstrual cycle in any way?