I swapped from driver to passenger seat once and managed to twist in some really awkward fashion and was hunched it felt like my rib twisted something digging in my upper left in chest under boob severe pain but stretched and it went, talking seconds/minute. All ok thought this just happens. Had this again the other night whilst umm raising my legs, excruciating had to stretch out straight instead of hunching and the thing digging in clicked back in place. Is this a slipped rib or something or what is it does everyone get this at times all fine now but I have been a bit breathless at times on and off for years due to anxiety stress low iron etc etc it doesn't hurt now but just felt and I'm sure that side feels different to other side more pokey outy and very slightly tender if I poke it but not really.