There are many reasons for breast swelling. Under normal physiological conditions, mostly seen before menstruation and during ovulation, breast swelling may occur due to changes in the body’s hormone levels resulting in breast engorgement. Breast swelling can also occur after pregnancy, due to further development of the breast gland. In pathological cases, the presence of chest swelling, lobular hyperplasia, breast fibroids and other diseases require a visit to the doctor for breast ultrasound and, if necessary, mammogram to find out where the disease is and give appropriate treatment. If you have breast swelling and pain during breastfeeding, and if it is accompanied by fever, it is mostly considered to be acute mastitis, and you need to continue to give antibiotic medication under the guidance of your doctor.