what you describe pushes one to think of a heart pathology or failure or lung disease. The simplest test that could actually guide us so much is a Chest X ray
. Out of that, I could clinical examination, a Electrocardiogram and chest x ray and lab tests shall be run which shall tell exactly whether you got a heart or lung pathology, or something else.
A good and proper diagnosis shall remain the mainstay of the treatment. Consult your internist or cardiologist for a proper evaluation.