My little dog Oscar isn't doing so well :[

We aren't really sure whats wrong with him. At first we thought he just had an allergic skin outbreak and he started to get better then got all worse again.
He's been to the vet already, and we've been trying to take care of him. Though that all happened Wednesday of this week and all he's been doing is laying in his bed sleeping all day.

He had to get stitches due to getting a skin sample thingy or something done. and of course that makes you not wanna do anything, plus he had work on his mouth some. But again, wednesday.

We're worried about the little guy. He hasn't moved from his bed on his own, and he hardly eats. He is drinking water, but that isn't enough but its better than nothing.

Like right now, he is laying in his bed trying to go back to sleep. Seeing him like this is really putting us all in a depressed mood.
He use to be such a happy little dog, playing with the other two and running beside us when we would walk around. Now, he just lays there and doesn't move, he doesn't even bark when one of us comes home.

So I am a little upset, because I'm worried about my little buddy. All three of my dogs are like little furry four legged brothers to me and I love em. so I really hope Oscar gets better and nothing is horribly wrong with him