My right hip flexor (on the line where my leg meets my hip, exactly at the top but radiating inward) has had bouts of sharp pain & cramping for about a month now. If I try to push through during a flare up and squat anyway, I'm punished with a few days where I can't bend my leg well enough to climb stairs - not from pain, but from weakness and/or a total lack of control over my quads.

What's weird to me is that this pain started *after* I did a lot of work to stop knee slide and prevent leading with my left leg and "twisting" to my right out of the hole.

Here's a video of my last session.
squat 3-21-21 - YouTube

Any thoughts on recovery tactics? I've read you shouldn't stretch it or massage gun it, so I'm kind of at a loss.

I also row on an erg and hike with the dogs, so there's a potential the aggravation is coming from there, but most often I wake up with it the day after a heavy squat session, and then any of my normal activities aggravate it.