What you are explaining sounds like a milk bleb. It is common and can occur in many breast feeding situations. You will need to visit your gynac who will puncture the blend with a sterile needle. This is a painless and very quick process done in the doctor's office. If there is any discharge it can be wiped off. The doctor may prescribe some antiseptic for local application which will need to be wiped before feeding the baby. You should be able to start feeding the baby painlessly immediately after the bleb has been removed.