What is the reason for the vague pain under the right breast, first of all, we have to clarify what the nature of the pain under the right breast is, such as needle-like, knife stabbing or dull pain, there is no dispersion to other places, in addition to the location of the pain is located in the skin, subcutaneous soft tissues, muscles, or is located in the internal chest cavity. Because the nature of the pain and the specific location of the pain is different, its cause is different, more common if it is a woman, there are breast hyperplasia, breast malignant tumor. Other causes of chest pain are intercostal neuralgia, and if the pain is internal to the chest cavity, it may be caused by pleurisy or pneumonia, or a lung infection involving the pleura. Therefore, to clarify the specific location and the nature of the pain, it is recommended to go to the hospital to take chest radiographs or do breast ultrasound, further examination to clarify the cause, so as to avoid delaying the condition.