Now and again i get a pain that's under my left rib and sometimes goes round to my back its at the bottom of my rib cage , it's mainly wen i'm sitting?

See answer: Pain under the left rib that radiates around to the back when sitting could be due to a number of causes. More often than not it's musculoskeletal in origin or a pinched nerve. Pain that has been intermittent for over a year, without getting worse, is less likely to be due to a serious cause. However if the pain concerns you, trust your intuition and see your physician for a proper diagnosis.