At this moment, during the night, if she can drink water, I would suggest that she take sips of water to keep hydrated. But if she can’t even tolerate the water, and she’s dehydrated, bring her to A&E. Otherwise, bring her to see a doctor tomorrow morning. She could have stomach flu, but the doctor would need to check for worrying signs as well as other conditions that may cause these symptoms. Are baby’s movements normal? More than 10 movements felt? If movements have decreased, also go to A&E (a hospital with O&G facilities) to have a check