Schatzi had a distemper shot yesterday, too (in the morning), and she slept most of the day. She wasn't her usual self either, and the injection site was so sore, she'd yelp if I touched it by accident. She went to bed early, and this morning she is finally back to herself, she's a mad ball of energy, running all over the house and eating up all of her food-
I'd probably give it 24 hours for your pup to get back to normal, hope she feels better real soon!