Hello, sorry to hear about Truff. It looks like she is having allergies and does not necessarily have to be associated with food aversions. Even if she wasn't allergic to her food previously, she could have developed an allergy just recently. Alternatively, Truff could also be allergic to things in her environment such as plants, pollen, house mites, and even other pets. If her redness continues, if she develops any itching, tearing of her eyes, or if she becomes very lethargic, then she should be evaluated by a veterinarian immediately. She may need medications to treat her allergies while undergoing a food trial. Hope this helps and best of luck.