im in year 10 1st lesson was pe it was trampolining and i went to do a back drop.i went back to far landed on my neck went back up into the air and again came down on neck and back =/ at first when i got off i couldn't breathe right and after i had to keep a straight back to bend down and still be in agony now 11hours later im sitting down and im rather still and i'm in pain any ideas what i've done?