Both my granddaughter and my grandson had similar issues after they switched to formula. The doctor tested my granddaughter and found that she was actually allergic to milk and not lactose intolerant. She was and still is allergic to soy. She was on a non-dairy, non soy formula recommended by her pediatrician. I don't remember it's name but I'll look it up. Non-dairy is the operative word here. Lactose free is not the same thing.
My grandson was diagnosed with GERD. He took a prescribed antacid and we kept him sitting up so that his stomach wasn't compressed by slouching. The easiest way to do this was to feed him while he was sitting in his baby carrier car seat. Both babies spit up alot even while breast feeding but they still thrived.
My granddaughter, tho not having the extreme difficulties of throwing up, also preferred sleeping in her infant car seat until she outgrew the seat.
As another mother said, it is very important to try one thing for a week or more before trying something else. The reason to try for several days is to notice if they tolerate it better over time. If they show improvement, even if it seems slight, in a few days keep feeding it to see if improvement continues.
Eating is new to babies. It takes time to adjust to digesting breast milk or formula of any kind. An adult issue that might help to understand this is a situation when one has surgery and their digestive system has been cut back to just liquids after a couple of days, or more, of no food at all. I always have gas and even at times feel nauseous for quite awhile after major surgery.(weeks not days) And a baby has the added possibility of their system not being fully developed.
Did you nurse your first child? Did you have success then? I'm wondering about why you stopped nursing so quickly when you said you had partial success. Partial success is common when one is learning something new. If you quit because of difficulties I'd recommend consulting a lactation specialist who might be able to help you thru those difficulties. My daughter went to a lactation clinic recommended by Providence Hospital, where she delivered, and was then able to continue nursing until several months later when her decision to quit was based on her preference and not on having difficulties. LaLeche League can also provide support and suggestions.
She had difficulties nursing because her nipples didn't become firm enough or something like that. They gave her a nipple shield which made a big difference.
Perhaps you quit because of your own health concerns. Then I understand stopping soon.
As another mother said, spitting up what seems like the whole bottle is not unusual amongst newborns. If you don't want to go back to nursing or pumping and trying a non dairy, non soy forumula doesn't work after a couple of weeks or if your baby is losing weight I highly recommend calling the pediatrician. Actually I think, if I were you, I'd call the doctor now. Are you able to weigh your baby? Losing weight during the first few weeks is dangerous. If
your baby is throwing everything up your baby is losing weight.
The formula that my granddaughter drank is Nutrimegen. It is expensive but worth it for your baby's health. I think that if it's prescribed because baby doesn't tolerate anything else that some insurances will help with the cost. My daughter got it thru the WIC program.