Sudden fever, chills and breast pain.

Hi mummies, i am not a breastfeeding mum but i do pump out my breastmilk at least 3 to 4 times a day. Today i have sudden chills, fever and breast pain from 1 side. And my head have been spinning just now, but feeling slightly better now. At least no chills and headache. Any suggestion from mummies on why i have sudden fever, chills and breastpain?