Mastitis when baby started daycare

My baby started daycare yesterday so I pumped yesterday about 2 my right breast started hurting woke up this morning like I got hit by a train ! Fever not really a lump but just more firm in a spot called ob they didn’t exam me they just sent in antibiotics and said if my fever doesn’t go away within 24 hours or I don’t feel better in 72 with antibiotics call back ! Has anybody else has this when u went back to work ? i know I can still nurse did antibiotics effect baby at all !? Experience ? This morning she had a more runny poop then normal and maybe slightly green this is before starting antibiotics and just nursing