When I was about 23 weeks I stepped on a newspaper that was on our door step (in the dark) and slipped backwards through the coat rack and landed on the shoe rack, putting my elbow through the sheet rock and making a big mess!
At first it didn't bother me, other then the fact that I twisted my elbow by not letting go of the door knob, until I woke up in the middle of the night to pee and couldn't move. I was SO SORE across my lower right midsection. It scared me so bad. I layed in bed for a few hours seeing if it would get better, and as a result I had a panic attack. So at that point I went to the ER.
They did an ultrasound and everything was fine. My aches and pains were all on the surface. I was stiff and sore for a few weeks and had to take stool softeners (sorry for TMI) because "those" muscles hurt to be used.. if you know what I mean.
As for your tail bone, I've broken it twice, and it bothers me a lot, especially as I get bigger. I'm told that the pressure will make it hurt, so if you've possibly injured your tail bone, I'd probably call your doctor.