If the pain is under the shoulder blade then it could be due to a problem with the stomach (like acidity, gastric reflux, hiatal hernia) or due to pancreatitis, ectopic
pregnancy (ruled out in
your case as you are a male) or in
the chest like angina or heart attack, pericarditis, pleuritis, pneumonia, pulmonary embolus, aortic dissection.
Since you have heaviness in chest, it could be any of the above conditions. It is difficult to diagnose on net.