This may sound silly but it really does work! Most of the time lumbar pain is caused by spasm. Hip Flexors are normally the culprit. The most painful is the Psoas muscle group, some of which cannot be touched as they are so deep into the abdominal wall.

When I have an exacerbation where my back is "out" I increase my water intake substantially to flush my muscles of the built up toxins. My lower back is surgical and I have bi-lateral radiculopathy's along with spinal stenosis so it always hurts. Sometimes I can't move at all.

I have found that during these times the hamstrings are really tight. If yu stretch those gently and then as they loosen just a bit stretch it aggressively most times it will loosen up pretty dramatically. Once you get the hamstring stretched then you can start stretching the hip flexors. Again Water is crucial! Give it a try!