Re: Sore nipple (just 1)
That sounds like it could be a bleb (http://kellymom.com/bf/concerns/mother/nipplebleb/) that has perhaps broken and turned into a small crack? It could also be a friction blister.
Try salt water rinses and a combination of 1% hydrocortisone cream and Bacitracin ointment (use pea-sized amount mixed and applied using a clean finger) to reduce inflammation and infection.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"