Oh, and I texted a couple from here, but I think I figured out my knee thing. Which is crazy and stupid that I've missed time if this is all it was, but....
I naturally pronate my foot significantly. When you look at me from behind, my ankles turn inward and I wear the inside of my soles substantially more than the outside. Well, yesterday during my short run, I suddenly realized I was running on the outside of my feet. And I couldn't remember if I always ran that way or not.
@pbm107 asked on Strava if the knee pain was better and it wasn't. It came back again after 1 mile. But I started running fast and it felt better. When I slowed down, it came back and for the last tenth of a mile I had that epiphany and made sure I pronated my foot while running (which I think I've always done anyway). And the pain went away.
So today I made sure I ran with my feet pronated and I had no pain whatsoever. We will see if it holds tomorrow and beyond, but if that's the case, then it's an easy fix. I'm not sure why or how or when I ever changed how I was striking except I wonder if it was some of the new shoes I got that were forcing me to land on the outside. I wore the Nike Zoomflys for the run today and they do feel like they want to push me toward an outside of the foot landing and I had to work against that.
We shall see, but I'm almost happier (and pissed) about that than the 5K result itself.