I get the equivalent of a Charlie Horse directly in between my breasts/sternum sometimes when Ibend over (i.e., to pick something up even if light in weight). It literally lasts a minute or two and I have to concentrate on relaxing in order for it to go away. It definitely is not my esophagus, stomach, heart burn or other. I feels like a muscle tensing up, but I don t know my own anatomy to say what it is. I m 40-years-old and it s been occurring for about a year. I haven t had any sort of injury...please advise, thank you.