Causes of excessive menstrating?

My best friend was in a car accident May 19 and since then she hasn't been off her period more than a week at a time. She's also bleeding heavier than normal. The way she wrecked is she was in the fast lane on the highway doing about 60 and someone clipped her in her quarter panel from the next lane over, causing her to spin out of control and hit the center median. When she went to Urgent Care, they told her she had whiplash and a sprained wrist but when she told them she was having sharp pains in her lower abdomen where the seatbelt was they disregarded it. She has a son that's 8 months old (he wasn't in the car with her nor anyone else) so some people told her it's because it hasn't been that long since she had a baby. She hasn't still been having the pains but the excessive bleeding is really concerning me. I'm making her go to the gyno next week but does anyone have any ideas what it might be?