Nipple pain and hard causes are as follows: 1. You should check yourself to see if there is any breakage or cracking at the nipple. If there is too much milk during breastfeeding, it can also cause nipple pain; 2. Nipple pain should exclude foreign bodies in the chest, or lumpy situations; 3. You should also check yourself to see if there is sudden physical exercise. If there has been, the lack of exercise leads to; 4, calculate the time of nipple pain, nipple pain is due to emotional or endocrine disorders, if it is an endocrine disorder, accompanied by symptoms of back pain or headache, may be the lack of blood circulation, lack of exercise; 5, in the process of female growth and development, there will also be nipple pain, the pain will not be very long, are 1-2 times a week, and the pain is also intermittent. If the patient’s age is 20-25 years old and there is still nipple pain, it is recommended to go to the hospital and have an examination.