It's highly doubtful that this is a food allergy, they are very rare. In dogs, enviro allergies are VERY common in this day and age...esp this time of year and throughout summer too. And in FL, they can be allll year round like they are here in AZ.
To read about how to approach and treat allergies, read this thread asap:
http://www.yorkietalk.com/forums/die...tart-here.html
Even though this isn't likely a food allergy, I would still get him on a high quality kibble like Natures Logic Venison kibble. You can get a 4# bag on Amazon.