After 25 years with lower back pain I can understand your frustration. I also tried every medication on the book and nothing worked. As Lut said, forget about chiropractors. If you can find somebody who does acupuncture, that will help you much more. It helped me for several years. Another thing you could try is rubbing in "Tiger Balm." It's used for sports injuries; it stinks but works well.
Good luck!