What Causes Severe Pain Under The Breast?

When I have to strain to use the bathroom I have severe pain up under my breast sometimes on both sides usually one side only. Also have the same type pain but more toward the outside of the breast area when I laugh a lot or to hard or sometimes when I am just sitting there it hits. It usually passes within a few minutes. I was wandering if I already have my gall bladder out what could this mean. Pain is very similar.