Can have low back pain and it be associated with your kidneys. I have had 3 kidney stones and my lower back always hurts when I have one. Have to have an xray and urine sample done to confirm it.
I can tell you that all of my digestive complaints (acid reflux, stomach ulcers, diverticulosis and related low back pain) all improved greatly when I started drinking a ton more water. I know it sounds simple and that it couldn't possibly be that easy. But try it. You have nothing to lose and it's free! The trick is to drink a full glass of water 20-30 mins before a meal. Helps your body digest properly. Good luck! Hope you feel better soon!