about 5 years ago, i was sparring with a speedy viet boxer and he landed a wicked chest shot on my sternum. it kind of knocked the breath out of me. after that i felt fine. fastforward couple months, and my chest starts feeling discomfort when i move. the pain/discomfort lessens and plateaus. after that, one day, i was twisting my body and i hear a popping sound and immediately the pain is relieved. but after awhile it comes back. since then its never gone away. i have gotten an x ray of my chest once and the doctors didnt notice it.
i know some weightlifters may encounter this problem.
here are some links i have found regarding this info: