Hello! I recently began to belly dance and working on shimmies I noticed something odd. There is a grinding sound in my sternum, it almost sounds as though the cartilage is rubbing against something else. When this occurs I get a little breathless and heart starts beating very quickly, and at times I'll get a bit of pain just below the sternum, near the the xiphoid. At times my sternum will pop, but it happens rather rarely. I don't have a lot of money nor the best of insurance, so I really can't afford to go to a doctor at the moment. I'm mainly wondering what it could be and how serious it may be.