The Psoas (so-as) muscles are twin stabilizers which attach from near the inside front hip protrusion through the stomach area and to the lower back. When these muscles get too tight, it changes the mechanics of the lower back support. Stretch those Psoas muscles by gently lowering a straightened leg off the side of the bed, and gently lift the opposite leg's knee towards your chest, pulling gently to stretch. Do this slowly on both sides.
Your facets, the side fins on your vertebrae, might be jamming as a result of Psoas shortening, so as you raise up, run both thumbs upwards close along each side of your spine in your lower back. Ideally, bend your knees when lifting up to get underneath your back, so to speak, not craning off in front of spinal support. Hope this helps. God bless!