What Could Obstruction In The Ribs While Bending/stretching Suggest?

when I bend over and pull on my toes to stretch my back... something gets stuck over a rib.. it's happened to me a number of times... this last time I really started to portude.. it felt like an intestine to me.. I could feel it lumping up.. and when I bent back over it finally went back into place... what is this and is a dangerous? Thanks! Sheila