This is a symptom of cystic hyperplasia of the breast, which is caused by an imbalance in the hormone levels of women, resulting in excessive hyperplasia and incomplete replenishment of the breast gland tissue, which is manifested as hidden pain, swelling and stabbing pain in the breast. The armpit is the location of the parametrium, which also contains normal breast tissue, and can also cause local pain, which can be triggered by anger or stressful work life. The pain can also occur due to muscle strain caused by excessive activity and strain on the upper limbs or chest, and the symptoms can improve significantly after resting or applying local heat. Acute mastitis can also cause pain in the breast, which mostly occurs during breastfeeding or when the breast ducts are blocked, so you should go to the hospital as soon as possible.