I have had back pain, sometimes very severe, due to a malformed last vertebrae.
The best relief I obtain is from:
1) Chinese acupuncture and TENS (transcutaneous electrical nerve stimulation). You can purchase a TENS machine for under $100, and use pads to direct the current where it helps the most.
Amazon.com: tens unit
2) Massage. A massage practitioner is good. I also own a G-5 massage machine. That tool is used by professional physical therapists, chiropractors and sports team trainers. It costs about $1,500 but is a miracle. (Google "G-5 massage".) Amazon has various models.
The handheld G5 is cheaper but the floor model works best. In 10 minutes you get the effect of a 60 minute physical hand-on massage.
Amazon.com: g5 massager
I bought two G5's over the years off of Ebay for around $500 each. They are made by General Physiotherapy. The G5 machines are so rugged that they last for 40 and 50 years, even longer. I would look for a newer unit however. Anyone can perform the massage with a G5. It is not hard work, nor tiring, as with physical full body massage.
3) Daily walks. I walk 3-5 miles daily, either on a treadmill at a fitness center, or on the beach (I live 2 minutes from the ocean).
4) FAR infrared sauna. 15-20 minutes 3-4 times week.
5) I second what was said about hydration.
I consider all of the above as part of my overall fitness and health regimen.
As I have aged I have to more carefully calculate my activities, and be aware that some physical actions (ESPECIALLY snow shoveling

). carry great risk of my back "going out" and spending 5-8 days recovering.