I was in a car accident September 4th, I was treated the next day for lower back pain. They took an x-ray and didn't find an slipped disks. I was given muscle relaxers for the pain. However, it has been a week and the pain is getting worse and is now in the middle of my back. What should I do?

Go back to the doctor, many pains and problems are not easily seen and many show up a week after a accident