This may sound strange, but get an adjustable air bed. I used to deal with a lot of back pain from playing racquetball or just picking up something wrong. Also, my wife had a similar issue, though no apparent cause, she literally couldn't sleep more than 5 hours a night without having extreme back aches. We invested in an adjustable air bed about 6 years ago, called a Comfortaire bed. Since buying it, I would never go back to a regular bed. The reason I think these types of beds really can't be beat is that when your back is hurt, what was comfortable in a bed before, probably isn't anymore. So, each night, I could adjust the bed to match the support my back needed. I found that my back healed much quicker, from taking a week to two to heal, to feeling better in a couple of days. My wife has no trouble with her back anymore, unless we spend a very long time in bed, like 10 hours or more. I don't believe brand matters much more than the price/warranty you can get, but everyone I shared my experience with that has bought a similar bed, say they would never go back.
No, I am not advertising any particular brand of bed, just relating my experience with you. Good luck!