Have you had her tested for allergies/intolerances?
I had a TON of issues with eating and with my stomach when I was younger. My dad was of the 'clean your plate' variety, so it was a constant source of anxiety. Many years later, as an adult, I've realized DAIRY IS NOT MY FRIEND! Once I cut dairy out of my diet I felt AMAZING. If I give into temptation and have some cheese or something I feel sooooo sick for like 2-3 days afterwards.
Having said all that - unless I am vomiting, I will still enjoy me some cookies or cupcakes or fruit snacks, lol. I have a serious sugar addiction. I once tried to sneak the whole jar of flintstone's vitamins as a kid because they were yummy!
If there are no digestive issues going on, you might want to consider therapy. Kids that are having issues that make them feel powerless will sometimes try to assert power over their lives in ways they know how to - one of which is eating.
