is the dog lethargic or lazy? Do you see a big change is behavior? Big changes in diet can cause stomach distress, but not fever, extreme thirst or sudden mood changes. I'd watch and maybe give it a day then call a vet. The call is free and you can get lots of advice from a vet w/o going in and paying for an appt. And Science Diet is not the best food but shouldn't hurt your dog either. Overpriced but not harmful.
"NEVER DO A MINOR INJURY TO A MAJOR ENEMY", Sun Tzu