Welcome to YT! Changing food may also help with the eye gunk -- I know it helped mine. Those corn allergies are awful.
Blue Buffalo is a good food. Do you have a specialty pet store around? I would highly recommend Innova.
Here's another idea - write some companies and ask for samples - I emailed a ton and got so much! Here's a thread with lots of addresses of good food :
http://www.yorkietalk.com/forums/yor...e-samples.html
Or you might want to consider home cooking - many swear by it and it makes you think about what your feeding yourself too
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http://www.yorkietalk.com/forums/yor...od-treats.html
A good book for deciding how to feed homecooked is Dr. Pitcairn's Complete guide to Natural Health for Dogs & Cats
If the spices don't work - there are products to use that are to help the poo eating including Solid Gold's SEP - yes that stands for what you think
Solid Gold Health Food for Pets
Also, here's a good site for buying food online at a discount
Pet Food Supplies Dog Cat Bird ... PetFoodDirect.com