Thank you guys for your posts. I really appreciate them.

I'm so happy to report that Barney has tested NEGATIVE for both FELV and FIV. The vet left a message this morning and I was scared to call back. Robin (the vet) said "I've got quite a bit to tell you. First, he's negative." I said "Miracles really do happen!!" and she laughed and said "they do!".
She said that they retested his thyroid and now it's low! She figures this is due to the meds and too much of them so he's going down to 1/2 a tablet a day instead of twice a day. She said this would also explain why he was so sleepy all the time.
His white blood cell count is still very high so the Convenia injection had no effect on it. She said that she thinks the high white blood cell count is due to the infection in his ears though she said there is still a chance he has FIP. But she said she doesn't think it's FIP but needed to tell me in case it is because it is contagious to other cats. So, I'm a bit worried about big beautiful Jack. They have been sniffing noses a few times Angela said. I asked her to keep them apart if she could. Apparently the litterbox is the main way it is transmitted. Jack does his business outside. I asked Robin if after visiting with Barney should I be putting all my clothes in the washer as soon as I get home and showering before I handle my cats (which I have been doing). She said it wouldn't hurt to maybe get some Barney coveralls that I could wear when I hold him just to be on the safe side.
They tested Barney's glucose and it is still up there but she said she wasn't surprised. It's too soon to see much improvement with that.
She said she's written up a game plan for Barney and went through it with me. First and foremost we need to get the infection under control and get him to gain weight. She sent Angela home with Surolan drops yesterday and today she said she wants to put him on Clavamox for a few weeks. I have 5 tablets on hand so she will prescribe 10 more that I'll pick up tomorrow.

She said that if he gains weight and the white blood cell count goes down, it would be fair to assume that he is FIP negative. She thinks that he would have already died by now if he did have it but it will be good when he turns a corner and starts to improve.

Well, that's the news. Gotta go to work now.