Hey, my baby was doing the same and she ended up having a milk allergy. But it was a LOT of vomit... Like pretty well everything she just ate and naturally she lost too much weight. Most babies spit up a little bit. Make sure you burp them half way through, sit them up to feed and try slow flow nipples. You could try giving the baby a little less formula and see if they still vomit... Could be too much for their little tummy.