Okay so my original plan was to just breastfeed but my son is now 2 weeks old and I'm not producing enough to satisfy him so we had him on similac advanced and it seemed to be okay because he was pooping every time he ate and it was nice and loose, then he started screaming when pooping so we switched to enfamil gentlease and he wouldn't even keep it down..he would throw it right up and his poops became thicker like putty and he still cries when he poops so now dr thinks he may be sensitive to lactose and we switched to similac sensitive...has this worked for anyone? So far he has only had 2 bottles of it but hasn't thrown up but also has not pooped. :/