Hi mama, the thing with formula is that you have to trial and error. So yes, it’s okay to change formula until you find one that suits him (best to see if your friends around can spare you some or find those which have smaller tins else your wallet…💸). My baby was previously on NAN Optipro HA (Now renamed as Supremepro HA) with no issues. And yes, probiotics helps my baby to poop well. I give her Biogaia on alternate days.
my one month old was on grow too when he was born. tried for about a week. and he didn't like the taste and had watery stools. changed formula and he drank a whole lot better and poops normal! you can try to change formula.