Knee ligament issue? (more explanation below)?

About 3 months ago, I fell directly on my left knee on a concrete floor. It hurt a lot after and it hurt for about a month, went away, came back, then went away again, and now its back. and its bad. It has to do with your PCL .. Last night at softball, I had to catch because our other catcher broke her thumb. I was in a lot of pain, but I didn't really tell anyone. When I got back to the dugout, I sat down, and All of a sudden I felt a burning and a sharp pain, along with something moving (it felt like something was pulling apart) in the back of me knee. I actually already have an MRI scheduled for thursday.. but do you think I finally tore it? Anything would help (: