My only suggestion when it comes to changing formulas is to stick to it for a week or so, otherwise by changing them around too often you don't really know which formula is causing what etc..

We went thru it with DD and DF kept changing formulas while he made up the bottles, and I had no idea why she was constipated one day, not settling the next - so I ask him what formula he was using and he's like "oh, I'm changing it up for her so she doesnt get bored of the same taste". My response was lol..."it's not like one is chocolate and the other is strawberry hun" he he...

But yeah, check with a MCHN re - what sort of formula to start with perhaps.

Good luck!