I have suffered from dull chest pain and shortness of breath for many years I have also been diagnosed with sleep apnea recently. I am currently using a CPAP machine. My doctor also told me that sleep apnea could be straining my muscles in the chest and causing inflammation of the costal cartilage, the structure that connects each rib to the sternum at the costosternal joint. This condition is called Costochondritis. Any update to your condition and did you confirm what your doctor told you? I am trying to understand my condition as well and try to find a solution to it.