on monday i did a somersault on the trampoline and when i landed on my feet my left leg just kicked in the air and my knee really hurt. i fell on the trampoline and i couldn't stretch it becuase it hurt too much. then i did p.e in school and it hurt when i ran and stretched it. then today stupidly i did another somersault and i did it again and it hurt more this time. i just tragged my leg along becuase it hurt when i out wieght on it. i went to get a ball and bent down and my leg just like fell becuase it hurt. what should i do? what have i done to my knee?
Sounds like cartliage problems, the knee has a safety mechanism if you injure / tear your cartliage. If you put too much pressure on it, it just gives way and you fall down. See a doctor to get it checked out.