Well this morning Max seems better. His eyes are brighter and his tail is wagging with more enthusiasm. Like he really means it now instead of the pathetic thump of the last couple days.
I found a vet to see him yesterday and he apparently has some sort of infection. He's also congested and in a bit of pain. The vet said it could go either way at this point. He did a panel to check his bodily functions and organs and said that the results were relatively good considering Max had been a starving stray just 8 months ago. Max is also up to 50 pounds now too. He still seems so freakin skinny though.
Anyway, now i get to pay the vet off for about 6 months and hopefully Max will be back to his old self in no time. It's looking hopeful at any rate.