Your ligaments connect bone to bone, whereas tendons connect muscle to bone. Stiffness would correspond to a tendon injury and ligament damage would result in problems with stabilization. I tore my MCL (opposite side of the LCL) in a football injury, and my leg would swing outward due to there not being a ligament to hold it straight. If it were a LCL injury, your leg would feel as if it were constantly "toe-ing in". I would definitely ice it up and see if that takes some inflammation out of the knee area. Then see a doc if it feels any worse.. Good luck and heal up soon!