What Are The Uses And Side Effects Of Levonelle Pill?

Hi, I recently had a very bad experience where I went out and got very drunk and ended up sleeping with a man that I did know, but not very well. I'm 20 years old and have always had normal, regular periods. I didn't have a very good recollection of the incident but the man confirmed the next morning that we did use a condom. However, I took Levonelle One Step emergency contraception that morning just to be safe. A week after taking it I had vaginal bleeding and assumed it was an early period due to the pill. However, it is now just over a week since that bleeding stopped and today I started bleeding again, lightly.
The sex happened on 4th August and I took the pill on 5th August. The first bleeding started on 11th August and finished on 15th/16th August. It is now 26th August and I'm bleeding again. Before the incident my period always came around this time at the end of the month. Could it be that the first bleeding was simply due to the pill and that this is my actual period?
Please help as I am very worried!