My 9 week old son spits up frequently and at any time. His pediatrician diagnosed him with acid reflux and sent us home with Similac for Spit Up. I understand most babies have this and it will eventually go away. But it's so frequent and at any time that it was recommended to try the formula change. He's only been on it a full day and I haven't seen a noticeable change in spitting up. The formula is also hard to mix and is clumpy. If you mix it too much, it's foamy. Anyone out there with experience with the Similac for Spit Up or the Enfamil AR? Any feedback would be greatly appreciated.