I'm 23 and have noticed a persistent dull pain under the second-to-last rib on the left side of my chest, about 23 inches below my left nipple. It's been happening for around 12 days now, mainly during deep breaths or when I try to stretch by pushing my chest out. I've never felt this pain before, and I'm starting to get worried because we do have a family history of high blood pressure and heart attacksmy grandfather and father, specifically. I've also been smoking tobacco for the last three years. Do you think this is something serious I should be worried about?