You should see a doctor, of course, but if they try to get you into surgery, I suggest you at least try exercise first. Proper gentle toning and stretching exercises done daily are the best thing for a bad back. Two years ago I could barely walk. Stretching through Yoga has totally erased back pain for me and I'm back to all my regular activities!

I agree with Dana, and also have a suggestion: There's a particular stretching excersize which I'd strongly recommend to you.
This is what to do: lay down flat on your back on a semi-hard surface (thin carpet), then bring your legs all the way to your chest (or as close as you can), then bring your arms around your shins to clamp your legs in place, and roll back and forth from north to south. I'd go 20-25 minutes at this stretch.

I of myself only have back pain sometimes after I wrongly lift weights, after which I stretch in this manner and the pain either goes away or greatly diminishes. My grandfather, who experiences back troubles often, has taught me the trick. I hope it may be of some help to you.
Patrick