What's a simple, cheap treatment for my back pain?

I did not know: There is no cheap way there right way, by finding the underline problems then we could recommend the treatment.

Nothing good is free: Sorry. No easy answer here. Though your current activity may be limited with pain, exercise is a good remedy. But it does take a significant investment on your part. Look into a beginners hatha yoga class. It will help strengthen your "core" - basically muscles from your chest down to your knees - to better support your back through all kinds of activities. See your doctor before you start.