If the discomfort of the left side of the chest needs to be judged according to the specific location and nature, if the discomfort is simply the swelling and pain of the breast, it needs to be considered as mastopathy, this discomfort appears along with the menstrual cycle, and the symptoms are obviously relieved after the onset of menstruation, you can take oral medication for symptomatic treatment, such as mastopathy elimination, prolotherapy, etc. Usually try to keep a happy mood, do not be too stressed, do not get angry, you can do an ultrasound examination to confirm the diagnosis. If the discomfort is in the precordial region of the left lower chest edge, you also need to consider the discomfort caused by heart disease, the more common are myocardial infarction, arrhythmia, etc., you need to go to the cardiology department and do an electrocardiogram to diagnose. If the cause is chest and lung disease, it can also lead to chest discomfort, try to go to the regular hospital to confirm the diagnosis, and then the symptomatic treatment.