Bleeding for a month?!

Okay so last month I took plan B after my fiance and I had an accident and I got my period 5 days early this month (on the 10th & it ended on the 13th) a few days went by without bleeding but then I noticed that I was starting to spot and it went on for a week and last night my fiance and I had sex and this morning I started bleeding heavier than before so I went to put a tampon in and it hurt, and I've had this aching in my uterus ever since. Any idea what is wrong with me?