I suggest you visit your healthcare provider so they can ***** the damages. It could be nothing, but better safe than sorry. Good luck!
If it is moving, it could be a clot. By all means, call your doctor or go to the ER or Urgent Care to have it diagnosed. Waiting could be a bad thing.
It does sound that you may have internal bruising and/or a break.
It would be wise to see your GP or go to ER if you are able with a doctor's referral for a examination by a medical professional and a possible x-ray to assess any damage and if there is any.
Best wishes.