Major stomach/ chest pain!!! Ideas?

So for the past few days I have had some serious pain and discomfort. It is like right under my sternum and above my stomach. It feels more stomach related though. I have difficulty breathing, eating, and sitting. It literally just feels like this awful pressure, as though somebody put a softball under my ribs and on top of my stomach. There is tenderness when i feel the area in question, accompanied by pain, but no real noticable knot. Please help me figure this out. It feels like having gas buildup, having a heart attack, and feeling starved all at the same time. Any ideas??