Well first off i'd try going grain free, most of these replace grains with potato (Grains are likely the cause). If shes still having trouble it may be the meat, it may be the potato...
If its the meat then an alternative would be Solid Gold Barking at the moon which uses mostly fish and only some mammal meat, and instead of grains, potato is used. Fish is usually more tolerable.
If its the potato causing problems, natures variety food called "Instinct" sells grain free which uses tapioca instead of grains or potato, which has been shown to be the most hypoallergenic grain replacement for dogs, bar none. 90% of the protein is from the meat in this food as well.
Never had any experience with eagle pack, but wellness "CORE" is grain free which you could try.