I would call the vet and ask if he could be having a reaction to the shots after almost a week. Did he get a lepto vaccine? Some times they have a reaction to that, but usually faster than this. he may be just having an off day, or cutting teeth. Does he seem hot? Or is he acting like he hurts somewhere? If not, he probably is fine. Just don't let him go too long with out eating, he may get shakey.
