I think you need a group-effort:
1. sports chiropractor
2. exercise physiologist
3. physical therapist
There was actually a sports-centre here that had them all and they each focus on a separate area of specialty. I was taken out for over 2 months when I started biking due to pulling my back out. The doctor prescribed pain-killers and bed-rest; recommended I stop riding. That was fine since I couldn't even lift my arm without pain. The PT and chiropractor actually helped the recovery rather than just mask the pain symptoms with drugs. When I was well enough to walk again, the PT and physiologist helped design a gym program to strengthen my back. My legs were super-strong from 13 years of running track, cross-country, football (American soccer). But none of those sports required much back-strength compared to cycling, so that's why I hurt it. So another month of vigorous strength-training in the gym with weights and machines strengthen my back-muscles by 4-5x. Finally, I was ready to get back on the bike and I haven't had any back issues since.
So... I suspect you have multiple areas that you need to look into, immediate and long-term.
1. therapy and recovery
2. fit - your seat may be too low and too far back, causes many more problems than being too high and too far forward
3. form - you may be mashing big gears, higher-RPMs in circular motion will require lower peak muscle-efforts for the same power-output, thus relieving the load on the knees
You should back up and examine the big-picture and cure the issue and causes. An in-the-moment fix of the pain symptoms may still have the potential of recurring injuries. Good luck.
Last edited by DannoXYZ; 11-28-05 at 10:12 PM.