I had the same thing and it turned out to be a clogged duct. I was so confused because everywhere I read said that redness mastitis. But, I never had shivers, or a fever, or flu like symptoms - just the red spot and some pain in my breast. I just massaged it out in the shower, made sure my baby emptied the breast completely and massaged while she ate, and kept heat on it and massaged it through the day. I loosened up whatever it was and the redness was gone the next day. So, as long as you don't have a fever or signs of infection, it's probably just a clogged duct. But, if it is a clogged duct, you gotta work fast to get it cleared before it gets worse.