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.