Hmmm…..maybe your knee experienced a little too much shear from parkour. I know whenever I do a lot of box jumps or running, especially downhill, that can wreck your quadriceps. Also, the popliteus*(sp) is a muscle on the back side of the knee that is important in extension and the upper head of the gastrocnemius can become irritated as well. Watch this video and see if any of that helps I know that when my calves get tight the shins have to pick up the slack and this causes all sorts of problems ranging from knee pain to borderline compartment syndrome(extremely painful and overrated imo).

http://www.mobilitywod.com/2011/07/episode-279-mob-those-lower-leg-bits/

Let me know if you need any other links I’m wondering what your knee pain is originating from! The lacrosse ball wedged between the fibula/upper gastroc and hamstring can really help loosen up all that junky tissue. Just make sure you don’t hit a nerve!