DS is 3 wks old. He is getting pumped BM through the bottle during the day and formula at night.
How do you know if the formula isnt agreeing with him?
He passes ALOT of gas, pretty loudly, but that's throughout the day. We use Similac with the blue lid.

Re: Silly formula question!
I take cues from baby - DD spit up Similac Advance almost every feeding, even after being burped.
We switched to a different/sensitive brand and she has been fine. She also burps a lot easier now.
DS spit up when he took Similac, was constipated with Enfamil and had gas that was clearly painful while on Babies R Us milk based. Now we use Babies R Us gentle and he has no trouble. He has gas some and it's loud but he's not crying through it. If he has painfull gas I'd switch otherwise I think it's alright.