Yes, battled with your
Yes, battled with your symptoms for years until I found out it was a torque in my SI joints, one was twisting one direction, and the other, the other direction. It affects the entire spine from neck to the tailbone, and therefore everything attached to it. The stiffness and tightness it causes is almost worse than the actual pain, as it is dull and constant, with periodic acute, sharp pains (in the sciatic nerve, etc.) If it hasn't already it will affect your shoulders, neck, jaw, knees, ankles, etc., eventually.
Here is what I follow and as long as I do it regularly, it keeps my SI joints, and hips, in place. Richard DonTigny, PT, is a master of the SI joints.
http://www.kalindra.com/Dontigny/homeprogram.pdf
The force needed to put the SI joints in place is immense. I would suggest using a band for his exercises, instead of your arms. And it needs to be a super thick heavy band such as the one I use, which is this one (tube bands don't cut it):
http://www.amazon.com/Stretch-FlexBand-Light-Purple-Resistance/dp/B002ZQE62A/ref=sr_1_2?ie=UTF8&qid=1325805425&sr=8-2
Secondly, get some pelvic blocks, such as these:
http://www.amazon.com/Core-Products-930-Adult-Pelvic/dp/B000HSUV86/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1325805555&sr=1-1
Learn how to do "Sacro-Occipital blocking" using these blocks. It basically "resets" your SI joints. It is easy and very effective. This book, is expensive, but discusses how to do sacro-occipital blocking. You could check it out from the library and make copies of the diagrams that show you how. I have tried looking online for these doctors' free diagrams, but can not find any.
http://www.amazon.com/Positional-Release-Techniques-DVD-ROM-Chaitow/dp/0443101159/ref=sr_1_1?s=books&ie=UTF8&qid=1325807115&sr=1-1