I believe when you experience pain, the first form of self-treatment should most often be ice. Pain is usually caused by inflammation. And to get that pain relief, we need to bring the imflammation/swelling down. Ice packs are the most efficient way to ease the pain.
My preferred ice packs are the ones I use in the clinic. They are gel; so they can mold around your body. And they are also larger in size; enabling them to cover larger body areas - such as your entire low back.
*I also have these for sale at my clinic and you are always welcome to stop by to purchase one. But as an option, I always like to offer is the "homemade" version of icepacks. Below is the recipe.
1 gallon plastic freezer bags
2 cups water
1 cup rubbing alcohol
Fill the plastic freezer bag with 1 cup of rubbing alcohol and 2 cups of water.
Try to get as much air out of the freezer bag before sealing it shut.
Place the bag and its contents inside a second freezer bag to contain any leakage.
Leave the bag in the freezer for at least an hour.
When it's ready, place a towel between the gel pack and bare skin to avoid burning the skin.