I'd definitely start with simple stretching, especially focusing on your hip flexors as this is generally where back issues begin. Also sauna always helps me out, helps your back and your overall mood!
I've had good luck with them, just have to be picky. I always make sure I know what the damage was and who fixed it. Make sure it was professionally done and I always avoid anything with front end damage.
Sawyer squeeze has been my go to, super light and easy to use. You can either gravity filter or "squeeze" for large amounts or put it directly on your water bottle or hydration pack. Can get pretty slow if water is super silty but a simple back flush of the filter normally solves this issue.