I also get bad back pain and sciatica (sp??), and unfortunately our insurance doesn't cover a chiro, and we just don't have the extra $ to cover it...
What I do find that helps is stretching my psoas and hip flexors. Because of where those muslces connect (the psoas passes through the pelvic bones and inserts into the lower back, tightness through that muscle can lead to back pain (it pulls on the low back).
) is an example of how to stretch the psoas. If you are flexible and fit, you can also do the stretch kneeling on the back leg. I find it really helps me, hope it helps someone else