[LuvMySissy]

I've never been a cheerleader, but as a fitness professional have also had lots of injuries. The rule of thumb is RICE - Rest, Ice, Compression, Elevation.
A Motrin would probably help with inflammation and pain as well. If you don't feel better tomorrow, I would not practice - tell your coach and ask to see the trainer (if your school has one).

I'm not advocating lying, but If you think you need to see a doctor, you might just tell your mom it hurts and you don't know why as you don't remember doing anything to it. I've had lots of injuries that I can't explain......