Whenever nipple pain begins again after a period of no nipple pain,
think Candida.  The fact that this mother mastitis, presumably treated
with antibiotics is supportive evidence.  Teeth do *not* cause abrasions
unless the baby bites.

Milk blister is another cause of new pain, but that is obvious on
looking.

I would treat with gentian violet just on the basis of the story.

Jack Newman, MD, FRCPC