My puppy is throwing up bile!?? ???whats wrong?

last time she ate was monday night, she only had a little tiny tiny tiny pieces of a treat yesterday. she slept all day yesterday and today we took her to the vet. she threw up 12 times today in an hour! it is white foamy and yelllowish, so im guessing bile. last week she was in the vet because we all think she had a seizure. has this happened to anyone elses puppy. she is about 15 weeks, a shepherd mix