Sometimes, Not All The Time I Will Go To Lie

sometimes, not all the time I will go to lie down on a couch sideways and my knee does this thing and hurts so bad. something feels like it's slipped or stretched in there. I don't hear anything but it gets jammed up and hurts like crazy until I move it a certain way then the pain is gone. I think it's in the ligament on the left side of my knee because that's where i feel it.