I know you can bruise your tailbone during labor, and bone bruises take a long time to heal. However, the pain should be constant, not getting worse. You might want to see a doc to make sure you didn't crack or break your tailbone during labor. If the x-rays are clear, I'd reccomend you see a chiropractor. The tailbone has to swing back in after baby's birth (it swings out during third trimester to make space for delivery), and it sounds like something with that process is not going well for you. Have you tried PP binding? I've heard that can help a bit as well.