Boyfriend sick with cough for a day, having difficult time breathing. Says left side of his chest hurts all the time but more when deep breaths. Advice?

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 a course of prednisone may be needed. SEEK PROMPT EVALUATION FOR EKG/CXR & LABS.