Return to your doctor and as KenKeith suggests, get a reveiw of the chest pain and nitro connection.Our body's are put together with close proximity of windpipe, lungs, esophagus ( can spasm), and heart major vessels ( can spasm)/larger vessels so it is possible sometimes to get better similar complaints of pain.When I experience chest tightening or chest pain of cardiac origin, I find it difficult to take a deeper breath; this may not be the case in all people. Take care in noting your triggers that lead to the chest pain. Joan.
Can your doctor explain why your symptom of chest pain is helped with nitro? If there is an esophageal disorder, nitro will act on that pain as well as angina (chest pain related to the heart). Esophageal spasms can be the problem or coronary artery spasms. If a coronary spasm is not present during a test, the test may be negative.
Also, deep breath pain is usually not associated with a heart disorder. Possibly Inflammation of the lining around the lung (pleurisy) can cause chest pain that usually feels sharp, and often gets worse when you take a deep breath or cough.