We just started giving our son Similac as instructed by the Doctor. The Similac makes a RIDICULOUS amount of foam!! We have never had a formula make foam, and Similac matches the prepped amount with foam. What I mean is, if I pour 4 OZ water and 2 scoops of Similac as instructed, and shake, I will get a prepared bottle that is 5 OZ Formula, and 3 oz of FOAM!!! Baby just gags on this and starts burping mid-bottle. We have never had these problems. Any advice?