If it is sciatica, ice packs on the lower back for 20 minutes will reduce inflammation. (Wrap paper towel around the ice pack to protect your skin from frostbite.) It worked for me.
Heat packs will improve circulation.
Here is a reference:
"Ice packs can help those with sciatic pain. This type of treatment is easy to use at home and is beneficial for dealing with nerve inflammation. Using one for about 20 minutes at least one time a day can help reduce inflammation and temporarily numb pain."
https://www.allianceptp.com/sciatica-ice-packs-do-they-work-and-where-do-you-put-them#:~:text=Ice%20packs%20can%20help%20those,inflammation%20and%20temporarily%20numb%20pain.