In addition to what I posted earlier, I forgot to mention a recent treatment that worked for me. Not entirely lower back related but, it MAY be relevant. Recently, the wife and I started crossfit- it's brutal and awesome at the same time. One day, about 3 months in, we were doing a light deadlift routine and when I went to lift I felt a light soreness in my neck and a terrible shooting pain across both sides of my head. It felt as if fingers had come from the base of my head and "reached out" across both sides my brain clamping down and shooting hot liquid magma. I tried to lift anyway and it got worse. So, I went home.
I rested for a few days and tried to go back and lift and had the same issue.
I remembered that the "atlas" is the bone at the base of your head that helps to not only support that 12lb bowling ball of a noggin we all carry around but it also helps to situate the spine. Anyway, I was googling some atlas related searches and found a different chiropractic procedure called "Atlas Orthogonal" Here's a quick link to show you:
Anyway, I went to see the Chiropractor that did this. X-rays revealed my atlas was 5* out of place... He hit me with a few of the "treatments" within a few minutes and the pain was gone almost instantly. The treatment has that little metal rod close to the back of your jawbone. The Dr. steps on a foot pedal and the machine clicks. The rod does not move. There are no needles, no cracking or popping, nothing (seemed a little fishy to me until I felt the results).
The pain did return a few more times in greatly reduced fashion when I tried to lift again (against dr's orders) and once I refrained for about 1.5 -2 weeks and then did light, non-overhead stuff I was fine... Now I'm back to lifting heavier once again.
The plus to this is that my normally tight mid-back has seemed to have relaxed a bit and allowed for more effective massage therapy and increased movement during chiropractic sessions.
Not sure if it will help the lower back situation- it could, but worst case scenario- it can't hurt...
Just throwing some ideas out there. I've had that pinched sciatic nerve and know the pain. Couldn't walk, 30 minutes to get into the car and try to figure out a good way to sit...Yeah, I've been there. (Cannot stress enough the use of a GOOD, tough, massage therapist- a good one will attack your upper glutes with an elbow and crank your leg around- It WILL hurt. But the results will be worth it.
Good Luck