I once had a mother who developed terribly sore nipples whilst breastfeeding her baby and toddler. It appeared the toddler had hand, foot and mouth virus and passed it to the mother's nipples. The baby did not develop the virus. No treatment was required, other than allowing nature to take it's course and keeping the nipples aired as much as possible. It cleared within a day or two Yvette O'Dowd NMAA Breastfeeding Counsellor Melbourne, Australia