I would ask for a sample from you ped gi. My daughter had the same issue, even on nutramigen and alimentum because there are trace milk proteins in them. The gas pains were so horrible! It does take a week on neocate to see a difference, and they get constipated for that week so ask for a mild laxitive. You will also have to thicken it because it is a watery consistentcy. We thicken with simply thick, and now add oatmeal too, since she is bigger. (Stay away from rice!) Also, many moms get their neocate covered by insurance, you just have your doc. get a letter ready saying she needs it for nutrition. We are in the process of doing that and bidding on it on ebay for 1/2 the price. Good luck! Sarah