Dental yesterday - lethargic today

Bella had her dental (cleaning) yesterday. She was fine when I brought her home, eating, and acting normally. This morning she seemed fine.
When I came home three hours ago, she was curled up on the sofa, and has not moved.
I immediately gave her a pain shot and put her on a heating pad (on low, wrapped in towel).
I brought her a little bowl of water, but she won't drink.
What do I do? Is this normal?
Should I wait a while longer? Should I try to syringe water to her?

I'd say just let her be for a bit, she'll come around. Milo just went in for a dental at the end of january, and he laid low for a few days too. She'll feel better soon.