What Is The Cause Of Sore Abdomen?

I took Levonelle (the morning after pill) exactly a week ago. 5 days after, I started to bleed. The 1st day I bled - it was very light. By the 2nd day, the bleeding increased slighty. By today (the 3rd day), I have filled up my pad 3 times with blood. Immediately after passing out urine, I experience a tingling sensation around my vagina. I also have lower back aches as well as a sore abdomen. I am worried. Please advice.