I've been battling some lower back pain for awhile. I run once a week, try to stretch in the evenings, and even try to eat healthier (less fried and processed foods). But none of that seems to be helping. I do sit behind a computer for my work, which probably doesn't help. While on a run, I learned a new stretch.
Place one of your shins up against the wall (your shin should be parallel with the wall).
With your other leg, place your foot on the ground flat.
Try your best to straighten your upper body in a kneeling position.
As an added bonus, try raising your arms up in the air for a deeper stretch.
For me, just getting to step is is a huge challenge. I can't even get close to straightening my upper body or raising my arms above my head. To help with getting my to this point, having a chair in front me helps challenge myself without over doing it and causing injury. Luckily, this now becomes my opportunity, as this will likely be a effective stretch.
From what I understand, stretching out the hip flexor is important for lower back pain because it's the psoas muscles that help support the lower back. When the psoas muscle is too short (not stretched out), it's pulling your upper body forward into bad posture, which further amplifies lower back pain.
Try doing this stretch for a minute on each leg. A good chance to do this is during commercial breaks when watching TV. Best of all, this stretch requires no equipment.