Hi Steve, and welcome to the board. You're so sweet to be researching and trying to help your wife!
I would recommend going to a large university hospital at this point and seeing their specialists. Pain is there for a reason! If the specialists you've already seen aren't interested in following up, keep moving. Don't give up! The university hospitals generally are up on the very latest techniques and have attracted excellent physicians. Even if you have to drive a ways to get to one, I'd call and see what spine specialist she can see. Make sure they've done a fellowship, but if they're in a university hospital they almost certainly have.
Keep in mind that it could also be referred pain that seems like it's coming from her back, but is actually from someplace else (kidneys, etc.).
I hope she (and you!) can get the answers you both need!
Blessings,
Emily