I have had this looked at by my family Doctor and he said not to worry about it but I wanted a second opinion. I constantly have a tight feeling in my sternum it is definately bone or cartlige pain (doesnt feel like it is internal). I used to be able to pull my shoulders back by bringing my shoulder blades together and it would actually pop like when you crack your neck or back. Is there anything that I can do about this or should I see a specialist? I work out regularly and I am cautious not to overextend during weight training.