I fell and it hurts to walk

The craziest thing just happened. I was walking across my bedroom to go out the door and all of a sudden it felt like someone had jerked a rug out from under my feet! I felt myself falling and I tried to catch myself and I landed flat on my butt on the floor, banging my back against a cabinet. I was able to get up and I can walk ok but my butt/back hurts pretty bad right where my crack starts. How would I know if I sprained my tailbone? I can't afford to go to the doctor unfortunately. Has anyone else done this? If so, how long till it healed?