Guessing you've never had an MRI scan, Mike? Be useful would that. Try and push for one as at least they'll know exactly what they're dealing with. The exercise will be good mainly for strengthening the core to relieve strain and pressure on your vertebrae and discs, yes?
If you have never tried accupuncture, as in the proper, traditional Chinese one, give it a try. Worked for me a few years ago and definitely worth a go matey.
Y'know, with the bikes, sometimes a bike with a riding position where you just lean slightly forwards as opposed to sitting bolt upright can help, relieving pressure on the lower back.
And that career change sounds like a good thing to look into.: