What Causes Ribcage Pain, Lump With Indentation, Discomfort And Pain?

I have a dull annoying pain right below my rib cage. There is a small indentation and a bump that can be felt just to the left of it. I have had discomfort for the year or so but only within the last three months has there been this noticeable bump and indentation. It hurts when I dont't sit straight up. What could this be?