Formula struggles, baby getting sick

M

So a few weeks ago I had to stop breastfeeding my 1 month old because I was producing 100ml over a 14 hour period and my baby was starving.

He’s on Enfamil A+ (he has 4.5oz per feed) and I’ve noticed he keeps throwing it back up. Not all of it, but a generous amount. I burp him, the bottle’s warm, I make sure I don’t shake him, but for some reason, recently he keeps throwing it back up. His diapers are usually poppy and have pee in them so I know he’s getting enough, but I’m worried.

Any tips? What could cause this? I just feel bad because he can’t tell me what’s wrong and I feel so helpless to help him :c