A person who is having mild difficulty breathing may:
During an upper respiratory infection, swelling in the nasal passages and sinuses may cause some mild difficulty breathing. This is rarely serious, but it can be a nuisance.
Chest wall pain may cause more rapid, shallow breathing but does not cause true shortness of breath. The pain will subside as your cough improves. True shortness of breath is a feeling that you cannot get enough air or that you are smothering.
Examples of conditions that can cause shortness of breath include:
WebMD Medical Reference from Healthwise