Not GP but personally I have found limiting caffeine consumption to help a lot with back pain. More than one cup of coffee (12g of beans) seems to result in exacerbation of any minor back pain I may have on that day. I also now take a day or two off from drinking any coffee after a few days of consumption. With this change, more sleep and some light stretching on some days I no longer have back pain. Oh, I also moved to a firm mattress.