Messed up my knee...Whats wrong with it?

i hurt my knee in soccer practice. i quickly changed directions, then it popped and whenever i put pressure on it, it crackled. now it doesnt hurt to put pressure, but i still dont have full motion 2 wks later. and it is still swollen on the bottom very inside and outside of my knee. it occasionally hurts to run and change directions, so ive been wearing a knee brace for soccer and its been fine. but it still hurts to straighten it out. ive iced it every night and taken ibuprofen before games. my trainer thinks it might be a meniscus tear but shes not positive. what is wrong with my knee and what will the treatment be?