his breath is different but not bad.
no drooling, well no more than his usual.
just under his eye and upper part of his cheek.
Whenever I hear of a dog who is feeling sick and has a swollen face, I immediately think that there could be one big thing going on:A dental abscess. Sometimes dogs get infections in their jaw, just like humans do. It's not always visable with the naked eye, so running some blood work to look for infection is one way to diagnose it. Another way is to use a dental probe and look for pockets under the gumline that could signify a problem. Unfortunately, the dog usually needs to be sedated for the second part, so having your regular vet run a little blood work would be a good place to start.
Just like in human dentistry, a dental abscess can turn fatal if the infection is left untreated. In a healthy dog like yours, it's pretty likely that all he's going to need is a round of antibiotics to start feeling better, so getting him in to the vet tomorrow is the way to go.
I hope this helps.