John, I'm having a problem with a "weird knee" too, and so far I haven't gotten an explanation. The podiatrist admits that my unusual gait (I have a problem foot which may be causing the problem knee) may be the cause. Some of this is Parkinson-related. I am also "old" - 56, so you could be right about that. I don't run ss you do, but I do walk for exercise. I plan to have the foot operated on in the fall, so I'll let you know if it affects the knee. pine`