Did i break my tailbone or did i just bruise it?

I was sitting ontop of my older sister and she slung me back and her heel hit my tailbone really hard. and it hurt i cant really sit on it now. and when someone touches it it hurts. It hurts when i walk sometimes to and whenever i sit on it too long and i finally get up. please help? what can i do to make it hurt less. is it just bruised? how long will it be bruised.