The painful breast nipple can be caused by various reasons among the includes when there is too much water in the breast tissue you will feel breast sore and painful nipple, other causes of sore painful breast include pregnancy, PMS which is the swelling and water retention due to hormonal balance also causes this, other causes includes oral contraceptives, breast size can also cause breast sore and painful nipple and sore nipple breast can also be as a symptom of a breast cancer
