You can get something they call intercostal chest pain, or bruised ribs, where you have pain in your rib cage which makes it hard to breath. If its something like that, it normally gets better.
There are more ominous things that can go on in the heart of course, just like there are creepy crawly things that run about in the night. Examples include prinzmetal angina and pericarditis. For the most part though the things that are really there are a whole lot less scary in the day time. To shed some light on it, go see your doc.
I really think you need to go and get checked out by a doctor. Ectopic beats can hurt and generally only hurt for a short while but the pain you are feeling sounds pretty intense so please do go and make an appointment with your doctor and/or cardiologist to get your heart checked out. It is very possibly it is nothing to worry about but it best you be seen by a doctor to decide that. Please keep us posted on how you are.