Thanks so much to everyone!!! I so appreciate all the input!

Ellie seems to have trouble with rice (woah, mamma, plain rice cakes were a disaster), peanut butter, legumes, cheese, and chicken, but is doing very well on Primal Duck. She absolutely loves apples, lettuce, basically anything and everything (including the foods to which she has a sensitivity), but too much of anything and she develops diarrhea very quickly (thank goodness for Honest Kitchen's Perfect Form). She currently has large swaths of puppy pyoderma on her belly, so something is still upsetting her immune system, but we have yet to put a finger on it. I am very grateful to everyone, thank you!