You need to get an MRI and see an orthopedic doctor. There are a number of things that it could be and there really isn't any way to know without an MRI.

If your family has health insurance you need to get your parents to take you to your family doctor and get a referral to an orthopedic specialist. He/she will likely immediately send you out for an MRI and based on those results will tell you what your injury is and the best way to deal with it.

PS. Make sure to get a second opinion. Some doctors will recommend surgery very quickly and once you have surgery you can't go back...the second opinion may give you an option other than surgery and if that's the case, take that first. You can always have surgery later.

definitely go to the dr and DEFINITELY get a 2nd opinion!!! My dad fell trimming the trees once and he was rushed to the emergency room, the NEW doctor there assured my dad nothing was wrong, it was just swollen give it a day or two ice it nothings broken it'll be fine...yea..ok except my dad cannot move his leg!!! obviously theres something wrong doc if the leg is completely immovable, he went to a different doctor and got a 2nd opinion and turns out he had completely torn the muscle off of the bone...ouch...so he ended up having to have surgery
...second opinions are always good to get