I had unprotected sex 11 days ago, on the 14th of January. I took Plan B pills within 24 hours. I am not on any birth control, and the condom was left inside me for the first time in my life. It came out the next day when I went to the bathroom. I started to have bleeding like a period within 5 days of taking Plan B. The "period" only lasted 3-4 days, quite light for 2 of them. Now I have lower abdominal pain, quite noticeable, plus severe back ache. Please advise.