Recently when i breathe i feel tightness in my upper left chest and going toward my left side of my neck, why?

R/O PERICARDITIS: You may have inflammation of the heart=PERICARDITIS vs inflammation of the lungs =PLEURITIS. Myocarditis is much more serious and can be suggested by an abnormal echo. Often they are post viral.They tend to resolve with rest/hydration /NSAID(indocin) if it persists as course of prednisone may be needed. You need a prompt evaluation EKG/CXR AND LABS. See your doctor for eval.