How to stop my legs hurting the next day after a lot of running?

Ok this may not seam like a lot but to me it is. first thing in the morning i did the bleep test (if you don't know what is is you have to run a 20m distance make it in time for the bleep and it gets faster and faster) any way i tryed really hard but i forgot to warm down after then at lin whitch was similar and i didn't get a chance to warm down much after that. And tomorow i have track in school so i have to run and get timed. But after all that i know my legs will hurt so much tomorow and i really need to do well in track. Should i have a warm bath or will that not help. And this is all compulsary at my school (they are big on fitness) so help