sick dog

I have a 5 year old female Cane Corso. We noticed a few days ago that she was vomiting but we just thought it would go away. After about 2 days, we took her to the ER. They didn’t find anything abnormal in her bloodwork or her xrays. No obstructions, besides a bit of dehydration they said she was okay. They gave her some fluids and send us home with some meds. They did have to sedate her while she was there because she was anxious and too scared to let the vet assess her without it. So, she’s been pretty out of it since she’s been home, which was last night. But she’s still lethargic, won’t eat or drink, and we can’t get her to take her medicine at all. We’re not sure what to do. They said to come back if she doesn’t improve but how soon is too soon to tell?