You probably bruised your tail bone.. or even cracked it. I did that once and Yes, it hurts for a long time! However there really is nothing to be done about it, after all what can they do put it in a sling? ;)... I know it really isn't funny trust me I KNOW... I am sorry, if the pain is bad enough you should go see a Dr anyway, at least they should be able to help with that much.
I fell like that 2 years ago... It was horrible!! It took almost a month to heal and no position was comfortable! Even laying in bed was painful! I did have an x-ray and my tailbone wasn't broken. Suddenly one day it just didn't hurt anymore. If you see your doctor they may have you get an x-ray and or help with pain meds for a short time. But most likely it is just badly bruised. Hope you start feeling better soon!!
Hahahaha i did that this winter. (not laughing at you) Turns out i feel so hard i like sprained my back, how i have no clue but thats what the doctors said. But it worked right after (still does that was a long time ago) Its probably just something else. If it was broken you wouldn't really be able to move. Your fine just try a hot bath to relax your muscles or something.