Pain in the right side of the breast near the armpit during breastfeeding may be due to acute mastitis causing armpit pain.
Acute mastitis is common in breastfeeding women, especially in primiparous women, and is most often preceded by a history of cracked and broken nipples and poor milk retention, manifested by redness, swelling, heat, pain and pus in the breast, and the axillary lymph nodes on the affected side may be enlarged and painful. laboratory tests may clarify the diagnosis.