So I fell in the bath over the side of the tub and landed directly onto my left breast, the pain was so severe I couldn't move my left arm I also have pretty small breasts so that could be a factor. This was two days ago, but the pain has been constant but still terrible. There is now bruising, but it feels like a bruise, and for the last three hours there's been a stabbing pain in my sternum that gets a lot worse when I breathe, could this be serious?