Me too. I went for physical therapy when my knee froze up, and I used to do the exercises for low back pain daily, then several times a week and less and less.
While I used to have back pain, the surprising thing to me is that my back isn’t hurting. It’s from the glutes all the way to the end of pinkie toe. Especially the butt, thigh, calf and heel.
Have you tried a big pillow or wedge underneath knees? That has helped me a lot.