Hello I'm 25 years old and I have a small pea sized movable lump to the left of my sternum. The lump is not visible I have to find it. It's been there for a while but I recently have been getting random sharp pains where the lump is. It is also painful when I move it around. My first thought was that it could be costochondritis because I do lift heavy at the gym but I'm not really sure. Any thoughts?