What Causes Painful Bulge In Breast When Bending Over?

Hi, may I answer your health queries right now ? Please type your query here...when I try to do a sit up or bend over too far, I get a very painful bulge right under my breast in the center of my body. It is right over my stomach I think. I have to sit up very straight and then I can feel it go back in. It has been happening for many years, but for some reason it has gotten worse in the last couple of months. I am a 53 year old female who has 3 children. It started after my third who is now 25. I am worried that it may no go back where it should someday.