I Had A Car Accident The Other Day, The Seat

I had a car accident the other day, the seat belt locked up on my lower abdomen and was sore at the time of the accident. I had no bruising and no lumps at the time so I didn't go to the doctor now 2 days later I have some bruises and a lump around an inch thick it goes diagonally up from my lower abdomen towards my belly button. Is this something I should be worried about?