Dog has a bug - not eating or drinking

[CheesyMcTudd]

Our 11 month old pup has a bug. We have been to see the vet, who said it is a bug and to just keep an eye and it will resolve itself in a few days but to go back if she starts violently vomitting or does downhill quickly.

Here's the bit I need help with, she hasn't eaten or drank a single thing since Wednesday afternoon (when she started showing signs of being unwell, saw vet yesterday). We have tried everything, wet food, roast chicken, ham.. Nothing. She is perkier today but still not eating or drinking, although did lick a piece of ham.

Is there any tricks I can try to get her to eat and drink?
I'm more concerned she isn't drinking than eating but don't know what to try. I'm not a new dog owner but I've never had a poorly dog before!