It is difficult to say without being able to examine the nipples, but it sounds like a contact dermatitis. 

Do you start a certain food or start brushing their teeth with something around the time you get red and sore?  

"All-purpose nipple ointment" or a mid-potency steroid (prescription) ointment may be necessary. But you might be able to get some improvement with 1% hydrocortisone ointment applied after every nursing or pumping to tell you that you are on the right track. Then you need to figure out what is getting on your nipples to bother you.  

Deep cracks at the base of the nipple may require breast shells for inverted nipples worn while awake to allow for healing by secondary intention. 
Kathy Leeper, MD, IBCLC
Lincoln, NE
Sent from my BlackBerry Smartphone provided by Alltel

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