Lactational mastitis is a condition in which the breast milk duct becomes clogged and infected while breastfeeding. There are many benefits to breastfeeding, but mastitis may occur during the first few months of breastfeeding while the milk supply is adjusting. The affected breast may have red painful lumps that are typically accompanied by fever and chills. Some patients may experience yeast mastitis, which is a yeast infection of the nipple and breast ducts. Contact your provider if you think you have mastitis. For more information and tips on breastfeeding, please visit our FAQ.