I had sex a few days later my regular period ended, but the condom came off. I took plan b within 24 hours of that happening. A week and a half later I started light cramping and light bleeding- not even enough to use a tampon. I have been experiencing the light bleeding now for a week. Is this a side effect? I have read about implantation bleeding and it doesn't seem to be that, as the blood is red and continuing for longer than that would typically be. Should I be concerned? My regular period would now be due in 3 days.