If my baby has been vomiting all night, should I call the doctor?

Yes. If the baby looks well today and eating normally you do not need to, but if the baby is not eating or drinking well or has a fever i will call the doctor for advice.
Yes. Babies do not have as much fluid reserve as older children or adults, so they can dehydrate much faster. And in very young babies, it may indicate the intestine is twisted or blocked, and that needs immediate attention. If the vomiting is particularily forceful, is bright yellow/green, or contains blood, call even sooner. Your doctor will know what to ask and help you determine how serious it is.