I love to run. Over the past few weeks, after running I get a pain on the side of my left knee. It hurts most during the motion of extending or bending the knee and in certain positions. The pain subsides after a day or two. There is no swelling. Any clues as to what the problem might be?

I always stretch before and after running and have tried running with a knee brace – neither seem to help. After the last run, I’ve decided to stop running for at least a month to let the injury heal.