Breastfeeding Strike?!

My little one nursed normally yesterday and last night started biting me (I did all the things I typically do to stop her that work - firm no, taking her off, taking a break) and found it hilarious! Today she has just refused to nurse at all. She has never taken a bottle but has been open to pumped milk in a sippy cup today for the first time. She has only had about four ounces, though, and it’s already 1:30 pm. Anyone else experience this or any advice? Thanks a million!