Had unprotected sex a week after periods, though he didn't ejaculate in me. Took i-pill the next day. Then around 6 days later my periods started. Lasted for 4 days. But three days ago, I kinda bled a little. But it wasn't a period type of bleeding. It was dark brown in colour. So could I be pregnant?? Could the bleeding be implantation bleeding? Please help. I'm tensed.