Formula

Has anyone had the issue where their baby can only take the pre-made formula verses making the bottle with the powder formula? My son was recently hospitalized at Children's for a night because his formula was causing him to projectile at every feeding which therefore made him lose weight. He is 8 weeks old and has been drinking the pre-made formula since we left the hospital because they gave us the rest of the ones he was using up there. It  doesn't make him throw up at all (just occasionally spitting from here to there). Now, whenever I have him on the powder formula I feel like he throws up every time I burp him. I just didn't know if that could be an option as to why he throws up so much is because we use the powder formula instead? He is on Nutramagen and takes 2oz every 2 hours or will take 3oz every 3 hours during the evenings.