Suggest Treatment For No Sensation Below Knee After Injury

last january (2009) i fell while curling and hurt my knee, i waited 3 weeks before i saw a doctor, and was barely able to walk at this point and when i saw the doctor, he said that there was nothing on the x-ray, and that i should stay off it for a few days.... since then (now june 2010) i have had so many tests that i cant count, i am barely able to walk on it, and when do my knee pops out of place, and hurts like crazy, it swells up, and so does my ankle and foot, when i sit cross legged for more then 5 mins, my leg from knee down goes numb, since the injury i lost the feeling from my knee to my toes for 4 months, now i only loose the feeling when sitting. and no doctors can figure out wat is going on, all tests come out negative for anything. im trying to get any suggestions as to what it might be?