He had some symptoms, not all. However, he starting improving on the same food, right after the test and about a two weeks after a heavy freeze. I ended up changing to a similar food that is easier to get after that. He's looking pretty good and feeling good as well. Based on everything I've tried, my vet and I believe it is environmental. I'll find out this Spring as I won't change anything (unless I have to for medical reasons) and see how the change in seasons affects him. And, because he is looking and feeling good, I'm waiting to see the derm vet.