My birthing class teacher said it is painful and from the outside feels like a pencil eraser.

Very very painful. Sometimes feels like a hard lump in your boob. The area will feel very warm. you may even run a fever. and it feels like no matter what you do the pain won't go away. All I can say is massage massage massage. In the shower, while pumping, while nursing bc you have to get rid of it before it causes an infection