I am almost 20 years old and am pretty active. I really enjoy running but recently (about a week ago) I ran 3 miles, which is really nothing for me, but about the middle of my run, i had this really sharp pain in my left knee. This particular knee has had complications like soreness and tightness before. This time though, the pain was much worse. I ended up running an 8 mile route yesterday and once again, the pain was horrible. I had to try and "walk it off" but that seems to intensify the pain. I feel pain on the lateral side of my knee. It hurts a lot to bend and then once bent, it also hurts to unbend it. Also, i can hardly walk normally. I have a limp...this is because it hurts too bad to bend my knee, therefore, i literally have to walk by dragging my left leg. It's that bad. Bending is not the only problem, when i add pressure to the left side, i can also feel a sharp pain to my patella. In addition, when i am laying down and attempt to raise my leg, it's harder than usual...big time! If you could please give me a few ideas of what might be wrong with my knee, that would be greatly appreciated!