Also would look out for mastitis here. I had it when DD was about 6 or 7 months old, fine one second, hit by a truck the next. Huge fever, red spot, lump, was awful. Lots of hot and cold facewashers, massaging, feeding and showers helped. Was offered antibiotics and a penicillin jab but didn't feel I needed it and got through without. Definitely have it looked at because it does come on fast.