Is it arthritis or an injury? Usually exercise is beneficial. What does your doctor say? Is there a Y with a pool convenient to you?
40 years ago I cracked a lower vertebra and have been working on it ever since. Nothing works better than the right exercise. The waterbed was the first thing that help reduce the back pain, then learning how to deal with arthritis & injuries helped worked wonders. Sure, they still act up, but less often and generally with less severity.
MDs gave me a stockpile of heavy duty pain meds (kidney stones, etc) and I never take them. With them, you can't tell what's going on with a kidney stone. But, sometimes, with problems like arthritis, one should take the knock-out pill because sometimes it absolutely needs resting.