I just got to say, I cracked a tailbone when young (I think) and also never went to the doctor because I was not being the sharpest tool in the shed when I injured myself. Let's just say jumping off a chair that swivels is a bad idea.
The pain was almost exactly what you said. I couldn't move for the longest time, and it hurt sooo bad. I'm now in my mid thirties, and it still gives me trouble from time to time.
I'm so sorry you hurt yourself that way. I just wanted to give you my supportive OW! Because unless you've done it, there's no way to get how much that hurts.