dear user tightness of chest and difficult breathing may refer to have chest infection or other causes chest infection or bronchial asthma or allergy as these causes bronchoconstriction and difficulty of breathing and you will feel tightness of chest especially with excercise and may feel that if you exposed to any odour or allergen some times there is myococrdial infarction may cause that and you need to do investigations for that as stress ecg test for diagnosis severe excercise also that causes your tightness and breathing difficulty considered main cause of these symptoms also psychological problems and stress and anxiety have great role in these symptoms so try to avoid stress and any anxiety troubles simply you need to do just investigations as x ray chest and ecg and may require sputum culture test to detect cause and you can discuss that with your doctor wish you healthy life