if you are breastfeeding sometimes within the first 2 weeks this happens due to possible engorgement because sometimes when your milk supply comes in it is more than baby can handle and also sometimes it happens when baby is not latching correctly. Are your breasts hot? That may be something to look into because you do not want to get fully engorged and then if you are not pumping it could lead to mastitis which is an infection and plugged milk ducts. If you have any questions you can always refer back to a lactation consultant at the hospital or through your local pregnancy clinic or even your local WIC office