Have you came menstrual if yes,it may be due to menstruation coming soon im also breastfeeding but i have experience nipples sore before menstrual came when my baby is 8months old...
Is your toddler nursing a lot? Your nipples might be sore from too much latching. You can use your breastmilk to ease the soreness or try applying lanolin.
Try applying coconut oil. It will help to ease.
Ovulating these few days?
Are you pregnant?
Anonymous