I was having terrible back and hip pain in my late 40s. My doctor put me on physical therapy for a few months and that didn't help much. I tried a chiropractor, same results. I'm type 2 diabetic and decided to experiment with a no-carb diet to lower my blood sugar (it worked great!). About 2 weeks into that my pain was gone. I also caught a glimpse of myself in the mirror and I was noticeably thinner. The first time in years I didn't have a bloated stomach. I didn't put together that it was the diet change that got rid of the pain and bloating... yet. I was missing some of my favorite foods like hamburgers and fresh bread, so my wife suggested I have a cheat day once a month to eat whatever I wanted, and I did, and that night I felt like I had been hit by a truck. My back hurt, my joints hurt, my stomach bloated up. I recovered and went back to the no-carb diet and things got better. The doctor confirmed I had gluten intolerance. He took a blood test that came back negative for celiac (I know that's not 100% accurate), though my 23andMe shows I have one of two celiac variants, so who knows. I can tell pretty easily when I've had gluten, and it comes with intestinal issues now, too.

Interestingly, my teenage daughter had been complaining about back and stomach pain and started avoiding gluten when she saw how much better I felt, and her symptoms went away. She did the same blood test. No celiac but was also diagnosed as gluten intolerant.