Extreme Pan in the Legs when walking and using it?

[Lucy Zhao]

i was giving friends piggyback rides and one of them jumped on my back by surprise and she ways a little more than the friends i was giving rides to at first and my leg twinged and my ankle felt like it cracked then shifted, then i collapsed to the ground and had to have my friends prop me up. i limp when i walk. but today another friend jumped on me and weighed even more and my ankle and knee twinged again, and of course i fell to the ground again and they had to flank me to class. it wasnt a life threatening situation so i didnt go to the nurse, but i limp when i walk. it is my right leg. i am right handed so i am stronger on my right side, but my ankle and knee just twinged and it hurt really bad when it happened. my parents wont take me to a doctor, but what do you think is wrong. my original guess was a sprain but having my leg jerk in an awkward angle just doesnt seem like a sprain. i am a tall person, so i might have injured other things when i hit the ground, but my leg is just killing me. ice doesnt do anything, and propping it up involves moving it. i just dont know what to do at this point besides going to the doctor. i am a strong person, they were 100 pounds at least. i just twinged.