“Pain under ribs”

So I have been trying to research for months and have found far too many explanations for my problem. Starting about a year ago I noticed while trying to stretch my back out twisting, something (felt like an organ) up under my ribs felt like it popped out and protruded. Also couldn’t breathe and I’m like frozen and can’t move. USUALLY within a few seconds, it’s going back down and you can see the bulge going back inside me. The first few times were always the right side right around the bottom of my ribs. Since then has happened on both sides of my ribs, sometimes my sides/back, and lower stomach. Gave natural birth almost 4 years ago and had an appendectomy almost 2 years ago.