woke up with a sharp pain just left of my sternum...felt 'internal', if that makes any sense. As the day progressed it feels more like bruising, or strain...relatively localized, painful when pressed. Problem is I didn't pull anything yesterday...& I have no external bruising. To be be accurate, I don't exercise regularly, so if I had pulled a muscle in chest I probably wouldn't feel it til the next day anyway...but this feels like an internal bruising, to the touch, from an impact or some trauma that I didn't have. And it feels much more 'dull' to the touch than it did this morning. My lower back has been hurting now as well, for the last 2 hours, but that happens now & again, so I don't know if there is a relation. I do smoke & drink