What Causes Hip Pain And Dropped HCG Levels After A Miscarriage?

My wife had a miscarriage at approximately 5 weeks (went to ER 4 days ago) and is now having pain on the left side of her hip (her left ovary). Is there any risk or health complications that need to be addressed, or is this a common issue after a miscarriage? The hcg level dropped from 320 to 71 on Sunday when we went to the ER.