it could be a trapped sciatic nerve, does it ever travel into your bum cheek and down your leg, dont put up with it get the doc to check it out, i was your age when my back started playing up, i left it to get worse before i went docs and had caused damage because of ignoring it.
best wishes deb
Sounds like a pinched nerve to me too. Do you ever have numbness or tingling that is hard to get rid of? Go get it checked. It could be a herniated disc or be as simple as needing a back adjustment. Whatever you do don't put it off. I did also and now only have 22% of the feeling from my waist down. If your dr does not think it can be taken care of with an adjustment make sure he orders a mri or ct scan with contrast. Best wishes, Sissie