It is common for babies to be sick - this is often in the early weeks as they get used to feeding and as their bodies develop. You can tell when your baby is vomiting, rather than just bringing up small amounts of milk, because there will be a lot more coming out. It can be frightening for your baby, so they are likely to cry. Lots of things can cause your baby to be sick.
Being sick often or lots of it, may be due to ‘gastric reflux’ where acid from the tummy can come up again. Babies can be grumpy and it can sometimes lead to poor feeding.