Mastitis is a breast inflammation usually caused by infection. It can happen to any woman, although mastitis is most common during the first 6 months of breast-feeding. It can leave a new mother feeling very tired and run-down. Add the illness to the demands of taking care of a newborn, and many women quit breast-feeding altogether. But you can continue to nurse your baby. In fact, breast-feeding usually helps to clear up infection, and nursing will not harm your baby.
Treatment: Try applying moist heat a few times a day, and nurse your baby frequently to keep the affected breast empty. (This may also help clear up any infection more quickly.) In the meantime, you can take ibuprofen to ease the pain. If your symptoms don't improve within 24 hours of trying these measures, see your healthcare provider. She may prescribe antibiotics, rest, and pain relievers in addition to hot compresses.
Diagnosis: Early stages of mastitis can present with local pain, redness, swelling, and warmth. Later stages also present with systemic symptoms like fever and flu-like symptoms and in rare cases an abscess can develop. However it is pretty common that symptoms develop very quickly without any warning. Except in severe cases it is not necessary to wean a nursling because of mastitis; in fact, nursing is the most effective way to remove the blockage and alleviate the symptoms. Sudden weaning can cause or exacerbate mastitis symptoms and cause hyponatremic shock in the infant.