gas and changing of formulas

cmoosey

This week we started the switch from Enfamil to Kirkland formula.  DS gets about 40% formula throughout the day, depending on how much I can pump.  This week he has been much gassier and farting a ton. Just farts, pooping maybe a little less than normal (1-2 times every 1-2 days).  He's been fussier today and today is the worst gas-wise. 

Is the increase in gas due the the changing of formula?  I have been trying to do it gradually so its not such a shock but perhaps it still wasn't gradual enough.  He only has 2 or 3 bottles with the mix and then it will be all Kirkland. 

How long do I give it with all Kirkland (if it doesn't get better) to switch to something else?  A week?