I have been facing this problem since last 1 and half years. It all started when I over stretched while lifting heavy weights doing chest exercise. I got slight inflammation but I ignored it for the next few weeks assuming it's normal muscle soreness post workout. Since then, the injury has not yet recovered completely. The area around sternum pains when I contract or over stretch. My day to day activities are fine but the pain is still there. I have consulted 2 physiotherapist and 2orthopdist