I have had the same symptoms and was diagnoised with Costochondritis after a trip to the ER on 6/26/04. I thought for sure I was having a heart attack. The pain was horrible. I had pain in my back around my shoulder blades and in the middle of my chest. At first I thought it was heartburn, which I almost never get, but the pain finally got so bad I couldn't move. My son happened to stop by and took me to the ER. After EKG and lab tests to rule out a heart attack, they diagnoised Costochondritis. Since then my doctor has put me on Relifin, which is a muscle relaxer and also Vicodin for pain. Some days it is so bad, even with medication, that I can't get out of bed. My doctor did say that one of the causes is stress and arthritis.