Stay away from chiropractors.
The absolute best thing for your lower back is walking and stretching- yoga is good.
Don't sit around - get moving as soon as you can stand it, and stay moving.
Get some good shoes with good support- the best things are Dansko Professional clogs.
They make your feet and legs work the way they should, and that helps your back muscles as well. There is a good reason you will see all the medical personnel wearing them in any hospital, and chefs in any restaurant. They make all the difference in the world, once you get used to them.
Go to an *orthopedic specialist* - not just your PCP. They can check you out and see what's going on, but often it's a combination of bad posture, bad support in your chair, not enough walking or stretching, and a little extra weight. But thewrong shoes can really kill you.
Oh, and one more thing. I thought I had major back problems. Turns out, it was pressure being applied to my spine by an aortic aneurysm that was threatening to burst. Get a chest xray, it could save your life.