can affect any part of the body.
I've sprained/strained my back occasionally since I was fourteen [serious sports injury a very long time ago!] And can only urge much of the advice spoken by others.
First off, heat-or heating pads....do not use more than 15-30 minutes on any given site.....While it feels good at first, opening up the circulation, after a time all that being 'open' is too much and your vascular system shuts it off. So more heat only defeats the purpose. If I need to, I do 15 mins on, rotate to another area nearby, then another 15min in the other place...and so on. Rotating to spots next to the really hurting area helps overall, because those other areas are compensating for the hurt one.
If you have access to a good orthopedist who specializes in backs get a look-see by them and get a program in action for exercise. There are dozens of safe, passive [lying on your back or stomach or side] exercises a person can do and not hurt themselves....I've been doing many for decades to keep things from getting worse-cause muscle spasms...especially those BIG muscles in your back, which are real killers in the not being able to sleep aspects. Hope this helps! = j