Try doing the Standing Quad Stretch at least a couple of times daily.
I had asked all manner of "body builders" and no one could tell me what my problem was.
Then I mentioned it to my Dad's Home Healthcare Nurse and she is the person who "diagnosed" my problem.
You have nothing to lose by trying it. Since you are a runner, you most likely do have the same problem as I did, it is really a runners problem but walkers suffer it too. I now try to remember to do the stretch after every single walk.
BTW, WTG! on worrying about that 20 lbs now! With all the tools at our fingertips today, take care of that 20 lbs now - don't let them build into a real problem like I did. This help wasn't available before the WWW came into existence.