Maybe jumper's knee, maybe not

[Zackcore]

When I attended University, I was a member of the swing dance club and was routinely practicing. I used to be a skateboarder, and am an avid road biker. Aside from that, I was doing Parkour (free-running) around the time of the injury.
I'm not sure what it is, but I have pain directly below the knee when I go up on my toes, go running, go up/down stairs, but not when biking or walking. The pain started during the swing dancing practices and only once I had my knee completely lock up on me. The pain managed to go away, but recently, after a quick sprint with a friend, it came back. The crazy thing, I had run with the same friend 3 days prior with no problems.
Sorry for the lengthy explanation, but I wanted to include as much information as possible. I was told I might need to stretch my quads more, but that was from a friend and I wanted a second opinion.
Thanks!

[Heidi]

Hi,

Jumpers knee is a possible explanation. This usually occurs in people who are involved in either jumping or running. It is basically micro-tears and inflammation of the patella tendon caused by excessive, repetitive strain on the tendon.

Have a look at this page for some more info on what causes it and how you can help treat it:

http://www.sportsinjuryclinic.net/cybertherapist/front/knee/indexjumpersknee.html

Your friend is right though, stretching the quads can help. As can icing after activity, getting your feet assessed to make sure your running shoes are right for you and strengthening other muscles such as the hip abductors.