Knee Pain

[Thorr777]

I've recently developed quite severe pain in my left knee. Is feels like it's directly below my kneecap. I'm only 20 so I assume I've simply injured it in some way. It only hurts when I'm using the muscle such as bending it with my legs strength or walking. In other words if I bend it using my arms it doesn't hurt at all. Although it does feel slightly uncomfortable. Any clues on what I might have done to it?

[LadyCG]

Why have you posted this question twice?

[Sqad]

You hadn't mentioned any swelling of you knee, you are young and nothing sinister springs to mind.
You haven't said for how long this has been a problem.
You may have developed what is known as Patellofemoral Pain Syndrome, common in young athletes.
Google it.