Hi!I am a very active 36 year old woman. I have had some leg injuries over the years but nothing more serious than a broken left and right leg ( at different times) and an injured IT band while training for a marathon. I occasionally have pain in both of my knees but nothing that prevents me from working out. Recently, however, I discovered a weird, moveable lump in my left knee to the left of the knee cap. You can actually see and feel it move as I bend my knee......its a fun little party trick. It doesn t hurt when I do it but it pops which feels strange. From time to time while I am walking my knee just gives out and hurts for a little. Any idea what it is? Im worried I tore my meniscus or MCL.