Enlarged ovary

I had an ultrasound done today and it showed that my left ovary was three times the size of my right ovary.  I have had a lot of lower abdomin (abdomen) pain and pain in my left lower back.  Could this be associated?  And could this be a sign of ovarian cancer?  If not, what else could cause an enlarged ovary and should I be worried.  The initial ultrasound was because I am having the pain, and abnormal bleeding, I had an IUD inserted 6 months ago and they were checking to see if it was in the correct spot (which it is).  My mom had cervical cancer when she was 22 so there is a history.  I am 28 years old and very scared.  What would I need to do???