Update:
Apparently the reason the dog was refusing food was because he was waiting for the cooked sausage he's been getting nightly.


He's a pretty smart dog and he knows his owner pretty well.
Dog is also eating dog food now that he's eaten his sausage. I think he knows that now it's dog food or nothing.
Shoulder is less swollen this morning, still painful to the touch.
Dog is ever more hyper and ecstatic to see people than last night and will do his full routine of tricks on command.
Dog finally accepted the last of his antibiotic this morning, and has enough anti-infective to last until Monday.
Hooray for getting better, though.