I don't know what's wrong, but I think you need to get to the doctor. If you have swelling in the abdomen, any number of things can be making this happen. Especially if this has happened in a very short time. If you were involved in a car accident recently, and were wearing a seat belt, it could be something from that, but I doubt that I could peg it like that. Go to the doctor o.k. Good luck.

 Could you be pregnant? That is the first thing i think of. Pregnancy causes back pain, and it can sometimes be early in pregnancy if a woman begins to change (body wise) early on.