I been told I have2 enlarged lymph node in chest what could that be. They told me they are 2 centimeters and now I get very short of breath?

Several causes. To make this diagnosis we would need a complete history and physical exam. Do you smoke cigarettes for instance? I am sure you have seen a doctor. Don't be shy of asking him direct questions, that's his job. There are several possible causes of your symptoms and you certainly deserve to know what it is in your case.