Hello,
For your symptoms, I suggest you to get an electrocardiogram, blood tests (cardiac markers), cardiac stress testing and stress ECHO done to rule out any cardiac cause of this tightness and chest pain.
Secondly it can be due to gastroesophageal reflux disease (GERD) that can causes belching and burning pain and mimics a heart condition. For this, avoid alcohol or drinks with caffeine in them, chocolate or spicy or greasy foods and instead take cold foods preferably liquids like milk and yoghurt. It also might help to avoid eating or drinking for two hours before you lie down. You may also need antacids and proton pump inhibitor drugs for controlling the stomach acid.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
It sounds like gerd or muscle problem heart problems usually don't just. Happen only when sitting IMO more with excersize shortness of breath with excersize is what I see most docs look for you seem to have a little anxiety to I don't know for sure but I know that anxiety brings in some weird stuff you wouldn't think it could its crazy. Ask for and echo good luck