I have a Muschovy/Mallard duckling four days old. He's eating a lot pretty much all the time on Chick/Duck Starter Grower. Today he sometimes acts like he's trying to throw up? But then he goes back to eating and acting like normal. This morning was the worst with several episodes and this afternoon I've seen one happen with less effects. Is he eating too much? I have loads of clean water and he goes back and forth to feed from grain to water. Can anybody let me know if this is normal or should I get this checked out at the vet. Don't want to lose him. Thanks in advance for any opinions.