Always pay attention to some accompanying symptoms, such as whether there will be frequent coughing, wheezing, shortness of breath. Or chest pain, purple lip and nail, breath holding. The former is mostly bad lung function, the latter is mostly bad heart function, to the hospital triage hanging different numbers to use. Uncomfortable when you can contain fast-acting heart or nitroglycerin (less than the therapeutic amount), to see if it will relieve significantly.
If there is no obvious problem with the organs, it may also be just a left chest muscle strain or overwork or something, or nerve sensitivity, in that case there is no need to worry. Usually pay attention to diet, choose low-salt and low-fat diet, appropriate exercise.