oh you poor thing Do you feel unwell at all? (could be a sign of mastitis).. could it be thrush? Try giving the ABA a call and see what they think, or even the nurse on call. Just put them in google and it will give you the number. If u cant handle the pain (it will be fine just to feed her from one side until you get it looked at if its just way too sore, just try and express a little out in the shower) head down to emergency and let them know... im sure there would be something they could do for you.