You need to rotate your hips.
Why this matters:
Try out this simple hip test (I call it the windshield wiper). The key is having your pelvis (butt bones) stay in contact with the floor as your hips rotate. Notice the difference between left and right (if any). If the knees don’t equally lean inward (internal rotation) as outward (external rotation), then you are limited in rotation. We’re looking for symmetry.
Insufficient hip rotation can place tension on the pelvis, as the loss of motion needs to be made up somewhere, and that often occurs in the spine. The low back will move too much, and this is not idea, so the pelvis and low back will tighten up. This will continue to build up like a snow ball: tight hips-> more movement at low back->tight low back/pinch-> tight hips, and so on.
If we can allow the hips to rotate, then the low back and spine can loosen up and do its normal job.
If you can’t cross one leg over the other, the stretches like pigeon, or even the figure 4 stretch can be hard. This new modified pigeon stretch can be a great way to add rotation in a low stakes way so that you don’t irritate your low back. I usually recommend 10-15 pulses per side (and you can spend more time on the tighter side!).
What stretches have you been doing to help with your pain?