I also heard this food issue is common when they start teething. My girl is 14 weeks old too and this week I've noticed she's feeling mouth pain, the teething is coming :/, so maybe it's similar for yours? Some of the other threads have suggested adding water to the kibble and soaking it for a few minutes to make it softer, if her mouth is bothering her it might be the pieces are too hard and meat is softer.
Or, maybe she just doesn't like the food you're feeding her. If she used to eat it before check to see if there were any recalls of your brand, people have reported a lot of times their dogs suddenly wont eat a food they used to eat or whatever and find out that the food had something wrong with it.