Two days after ending my period, I had unprotected sex with my ex boyfriend. He told me he came in me and I took a plan B pill the morning after. Four days later I started a light bleed for a couple days. It seems like my period but at the same time different. It's the lightest bleeding and brownish bleeding I've experience. No cramps whatsoever. Could this be a side of effect of the pill? Could I still possibly get pregnant?