I wouldn’t worry too much yogurt till they get better isn’t going to hurt them. Id even try giving them the deebees popsicles they have no added sugar so if they are picky with getting fluids down they have something. It’s hard to make sure they have a balance diet when they don’t feel good as long as they are eating something and staying hydrated that’s all that really matters.
Feed baby yogurt and fluids! And wait it out. Yogurt has protein and fat, carbs and sugar, even probiotics. it’s a pretty good thing to eat. Whatever baby wants baby gets when their sick in this house. Tylenol for fever and discomfort, lots of relaxing and parent cuddles.