I want to thank the people who mentioned Sun Salutation yoga poses. While I’ve always been pretty good about stretching before/after workouts and before/after bed, I hadn’t done a lot of bending backwards, as in the Sun Salutation (standing, near the beginning, then after you pass through a sort of pushup pose to where your hands and feet are on the ground and your back is arched as far back as you can). But, after the explanation from formosa fitness and others that the problem is largely from being hunched over all day at the desk and on the bike, I realized that’s true, and arching backwards like that was just what was needed. I believe it’s helped a lot.
Additionally, I’ve been doing various simple lower back exercises and I think they may be helping. Here’s a great bunch of exercises one can do at home:
bloombikeshop.com/bodyweight-exercise/ 
I expecially like the plank – try it if you’ve not done it before.
But most importantly, we finally threw out our huge, soft mattress that my wife and I have been complaining about for years and replaced it with a very firm one and DAMN, that was exactly what I needed.
Stretching and exercises have definitely helped, but I swear replacing the bed was far more helpful. 