Clogged milk duct
A blocked milk duct can arise because the baby has not drained the breast properly, by pressing the breast in the same place over and over, a tight bra or sleeping on the stomach. A clogged milk duct then manifests itself in the form of a painful, possibly red, or warm spot on the breast. Make sure this is fixed as soon as possible to prevent a breast infection. You do this by warming the spot well, so that the milk ducts open wider. Then you should massage the area when the baby is drinking, when you express or massage the area in the shower.