I have this back injury from playing high school football that has followed me for 15 years. Whenever I feel stress or have something on my mind, my lower back area tenses up. If I'm not thinking and make a sudden movement in this condition, it'll tear my lower back muscle and I'll be out of comission for a few days until it heals.
This was a regular occurrence until 2006 when it happened last, I tore it REALLY bad. I was down for a week. Ever since, I've found that if I stand for more than an hour, my lower back gets extremely stiff and achy. If I don't sit properly, or sit in a car for more than two hours, I will get aches and pains.
Radial or twisting stretching aggravates the condition. To keep the pain away I workout every other day with plenty of sit ups, leg stretches, lower back extensions, upper back presses, and the lower back stretches where you pull your knees up into your chest. I never could touch my toes before, but I can now. Stretching feels great overall and relieves a lot of the stress that causes the lower back tightness.
If I lie flat on my stomach and press my hands to my lower back and push it down toward my heels, I can feel a small pop that relieves some pressure and feels good. The best relief is when I lie flat on my back with my arms outstretched for awhile. Those sphinx/cobra/upward dog poses don't feel good to me, but I figure it's because my lower back problems are muscle related and not spine related, but I'll never know because the ---smurfin---' doctor won't refer me to the spine clinic. The bastard.
Good luck with your pain. I don't know your physical condition, but good exercise and stretching (to an extent) never hurt.
I haven't had an episode where it'll "go out" on me since '06 but if I slack off on exercise, I can feel it getting worse.