Milk Allergy or Acid Reflux?

My daughter was exclusively breastfed for 1 1/2 months but due to my demanding school schedule and her constant need to feed, I decided to switch her to Enfamil A+

She did well on this but it was very expensive and too much so for my budget so I switched her to a generic version which she was doing great on for about a week then started vomiting after every feed. She is constantly hiccuping/vomiting (projectile) and screaming her face off in between feedings or at feeding time. She will even refuse to eat at times  

She poops once a day which is pretty normal for her, but she screams in agony and arches her back so I am pretty sure it's her little tummy that is hurting.

Can babies develop an allergy to milk after a while? or could this be acid reflux?

when I say she vomits, im talking pretty much EVERYTHING she eats... not just little bits here and there.

i bought isomil advance tonight because it has the omega 3 & 6 like Enfamil A+ so I am hoping the soy base will help her a bit or make a positive difference and not give her bad gas :S I just want to get her on 1 formula and stick to it!

it's acid reflux...but she could either be allergic to milk or intolerant.

My son had acid reflux before we knew he had a full blown allergy to milk. But even after we put him on a hypoallergenic formula he still required thickening and medicine for the reflux.
You could try a soy formula...it works for some babies with dairy intolerance but some children also are intolerant to soy.
We used Nutramigen.

if she is projectile vomiting, she likely has pyloric reflux, however, it would be odd that it didn't present until now. what is likely making it worse is the formula taking longer to digest than breastmilk. arched back is also a telltale reflux sign.

my baby has milk protein sensitivity and reflux, my eldest had reflux as well. you should see a doctor and have her tested.