won't eat or drink

my daughter suddenly won't eat. She woke up at 3 AM, we tried feeding her and she wouldn't eat so we put her back to sleep, she woke up again and 7 and only drank 2 ounces and stayed up for an hour and went back down till 10, I tried giving her some baby food and she only had maybe 3 bites and wouldn't take more so I tried giving her another bottle and she refused it. She usually eats 6 ounces every 4-5 hours and eats food 3 times a day. what could it be??