I know probably most babies gone thru this stage whereby they reject their daily milk out of sudden. My son went through that once when he was an infant. We were very concerned when that happened. Luckily, a few days later he was back on the milk drinking.
Last Sunday morning, he woke up like other usual day. I prepared and warmed the milk just like before. Gave to him, he drank for 1 oz and then stopped. We tried many ways to have him drink it - changed to straw and cup, changed the nipple to sipper, use cold milk instead of warm, let him watch tv, and cradle him to drink. The latter one worked but he only finished 3 more oz. So we thought he wanted to go #2 that's why he didn't want to finish the milk first. Let him finished #2 which took forever. We managed to give him the rest of the milk in the car on the way to see a client of mine.
The second feeding for that day was ok. He managed to finish about 7oz. The night feeding is when it happened again. He was so tired that he didn't want to sleep. We gave him milk, he finished about 6oz. His usual intake was a full 9oz bottle. But he didn't want to sleep. And he didn't want the pacifier.
Motherhood is very tiring.