We did the similiar thing as SarasMommy above. Put my son on nutramigen, partly due to his insides being so full of gas and being allergic to formulas with milk. I breast fed but he had thrush and passed it onto me, and it was just too much. If you put him on nutramigen and give the intestines and belly and everything time to settle down, we took a little over a month, then began to introduce soy formula in with it. I would mix 4 cups water and formula and fill my bottles for the 24 hour day. I started with one scoop of soy and the other 15 scoops of nutramigen. Slowly upped the soy, we are now only 3 scoops of nutramigen and the other 13 soy. Every baby is different, but what I learned is suddenly switching formula is too harsh on their digestive system. So you have to mix it so their system adjusts to it, avoided all that gas and other problems. My boy is 12 weeks and so much happier now. Good luck!!
at 8:42 PM on Nov. 5, 2008