Have you recently been sick with a cough, or done any strenuous activities with your arms? I was having really bad chest pain near my right breastbone (felt like I injured my right boob) a couple weeks ago, and was diagnosed with Costochondritis - which is inflammation of the muscle near the rib cage and breastbone. What you're experiencing sounds a lot like this.
However, if the pain is not being relieved by taking an anti-inflammatory (ie ibuprofen), I would definitely have it checked out! They can do an x-ray (they did with me) to check for anything more serious, and even an EKG.
at 2:16 PM on Feb. 27, 2011