If breast swelling occurs 10 days before your period, it is generally not a phenomenon of pregnancy, because after pregnancy, estrogen in the body increases slowly, and breast enlargement, breast swelling and pain, and nipple and areola coloring gradually appear only after about 45 days of menopause. If breast tenderness occurs 10 days before menstruation, it is often caused by endocrine disorders, such as a relatively high secretion of estrogen and relatively low secretion of progesterone in the body, the breast tenderness will occur, and often accompanied by insomnia or emotional excitement, more sensitive symptoms occur. It is advisable to take oral vitamin B1 to effectively relieve premenstrual breast pain, and it is advisable to have an ultrasound examination of the breast after menstruation to rule out the possibility of organic lesions.