A long way back my squat form was pretty poor and I think this was the start of my low back problem.
I found out the muscle was the quadratus lumborum on the right side which was the source of the problems.
My QL feels like a hard dull ache. No sharp restricting pains. And in the right lower back area if I rub it my back feels crunchy and gritty.
Where my QL doesn’t seem to be working it seems to make other muscles pick up the slack when I’m standing. Sitting down feels normal.
Areas that pick up the slack. My IT band through to my knee aches, contraction round my hip,erector spinae,gluteus medius.
Seems to be different ones now and again not all those at once. I’ve tried stretching out a lot more than I was in lower back areas and freed up some tightness a bit.
I’ve tried some QL stretches too.
My QL just never seems to start doing it’s job again. I’m forever when standing resting on my left leg as standing on both feet feels uncomfortable.