Katy Bowman is my favorite resource for fixing chronic aches and pains, she has lots of information on physiologically correct movement and correcting longtime poor movement patterns. It can be kind of overwhelming poking through her site as there is a TON of information but I searched it for back pain and http://www.katysays.com/5-simple-ways-to-avoid-back-pain/ looks like a good place to start.
I luckily haven’t had to deal with major back pain though both of my parents have off an on so I do have a clue what you’re experiencing and I hope this can help. I found Katy this spring when I had a pinched nerve in my shoulder that multiple weeks of chiropractic visits was only barely touching. After realizing how off my spinal posture was (both incorrect pelvis tilt and rib shearing creating a major swayback) and straightening my feet while I walked, one week of just correcting things when I noticed I’d reverted was enough to eliminate the pain completely. It hasn’t come back and my occasional knee pain that I’ve had for the last 15 years has completely gone too. I’ve still got lots of bad habits that I’m trying to slowly change but I figure I’ve got a lifetime creating those movement patterns and I can give myself some time to work them out.
I hope she can help you to!