I think I get the same thing. I have had years of upper middle back pain and for the last 3 years I have had pain radiating to the front area. My heart has been checked and there is nothing wrong there. they can't find anything wrong so they say it's a structural thing. I still can't work out wht it is as it's happening more frequently. I get pain in my sternum but I also get a strong pressure on my chest/sternum area, and it feels like it restricts my breathing. I can't work out what brings it on but it just appears and disappears on its own. It's a horrible feeling, In the past I thought i was having a heart attack. I also have a hiatus hernia so i'm not sure if this could contribute to the pressure I feel? I would assume it is TMS as there seems to be nothing else it could be according to the doctors. Do you also get these symptoms like I get?