Mimi does the same thing. I worry too when she doesn't eat...& she'll vomit yellow bile cuz her stomach will be empty. So I end up mixing stuff in her kibble. She'll eat it for a week or two, then if I don't change the menu...she won't eat or pick at her kibble.
I've mixed very small amounts of: salmon oil, green beans, chicken w/white or brown rice, scrambled eggs, sweet potato, cottage cheese, whatever dogs can eat.
I also changed the kibble coupe of times. She seems to like Natural Balance Sweet Potato & Venison, they only have it in regular bites though.
You might need to change her kibble (gradually) & find the one she'll like & mix it up if you want, or shall I say...if she wants. lol