HELP PLEASE! Back pain, track meet tomorrow?

Today we were practicing high jump. and i ran too far and when i jumped over the bar my momentum carried me way too far forward and i ended up missing the mattress we were landing on and i landed on the gym floor really hard. it was okay at first, it hurt but i still practiced afterwards. but right now it hurts really bad, and i have been putting heat on it. i was told not to ice it? but i have a track meet tomorrow and i have to do hurtles and high jump. i dont want to quit or back out of it. do you have any ideas on what i should do for my back?