Don’t discount your feet as potentially being the reason why you have back pain.
An imbalance here will be magnified as the distortion builds from your legs to your knees, hips, pelvis and low back.
This can be a real effective technique to use. It may be slightly painful so take it slowly at first and gradually build up the pressure. If it is not the source of your low back pain it will at least give your feet a well deserved massage.
Again do it at night holding for 30 seconds at each point.