What Causes Painful Skin Welt On Spine?

Hi, I fell heavily on a shoe tree over a week ago, bruising myself at the top of my left glutes, about on a level with the base of my spine. The bruising is receding, but I still have a donut shaped welt there. This is quite firm and warm, and when I sit back e.g. On a car seat I get an excruciating burning pain. In addition, Because the welt is donut shaped I m worried I ve cut into/ damaged the muscle in the middle of the donut. Is this sort of welt and pain normal or should I go to a doctor for examination?