I just gave birth exactly 10 days ago, experiencing bad abdominal pains today. What could it be?

See your Ob-Gyne. I am concerned that you could have a problem with your uterus. Depending on the details of your delivery it is difficult to guess what this could be and it would be best to call your physician to discuss symptoms such as bleeding, fevers, urination or defecation as well as other associated conditions.
Unclear. You should visit your obstetrician for a checkup immediately. Or if you are really ill, go to the emergency room.