Look no further! I too have been having that symptom, on and off for years. Happens when I bend over, but mine is a few inches lower than the ribs so it also tends to happen if I wear tight pants and things like that. And my doctors have also told me not to worry about it and didn't even try to diagnose it.
But what's different between my case and most of the people on here, is that I also know exactly how to get rid of it because I had it go away for years and I know why it came back!
About six years ago, I started exercising because I was severely overweight and it was hindering me from doing active things with my children. I started gradually but daily, because making changes that stick, is all about habit. I excercized in my home, using only a floor mat, and I started with 5 minutes of yoga a day.
Several months in as I had been building up my workout to be more extensive, I also learned that 80% of weight loss is eating properly, while only 20% is exercising! No wonder I wasn't getting as much in the way of results as I'd like.
Armed with this knowledge, consistently exercising (by the end of my weight loss journey, I was exercising for 1-2 hours every day), and eating small (200-250 cal) balanced meals, 5-6 times per day, NOT dieting! I lost 80 Lbs over the course of two years, the right way.
And I kept it off for about a year. But due to some unrelated, emotional hard times that I hit in my personal life I started gaining it back and just like it took two years to lose it, it took about as long to gain it back. But because of all the muscle tone I had built, I am still 4 sizes smaller than before I started and way more toned, because muscle truly does weight more than fat.
But the MORAL of THIS STORY...
Is that...
During my entire weight loss journey, I STOPPED EXPERIENCING THIS SYMPTOM ENTIRELY!!! It only came back AFTER I gained the weight back.
So whoever it was that said their doctor told them to lose weight, that doctor was on the right track. And if you're experiencing this symptom but you are not overweight... then I would still recommend core exercises to tighten your abdominals because those muscles help keep everything in place, I've found. By the end of my work out years, I was doing 10 different types of core exercises every day, in addition to all the other types of exercise!
Start with the easier types of yoga core exercises, because those, done properly, can help you with other things like a bad back, etc. Lool up videos of beginner yoga online. Don't start with sit-ups people, you'll just discourage yourselves and you could make your symptoms a lot worse. Slow and steady wins the race!
Blessings in all things,
SashaMermaid