We switched from Isomil (we have milk allergies in the family, so we started her out with soy) to Good Start Supreme Soy, per the pediatrician's recommendation after DH had a rough night with DD. It was a Friday (we would have waited another day or so if it wasn't a Friday - another day or so would mean a trip to the ER instead of the pediatrician since it would be the weekend) and we wanted to rule out any real reason for the crying the previous night, such as a cold, ear infection, etc. Honestly, it could have been DH or just that the baby had a bad day; it was only one night and before and after she was fine. The doctor said she's fine and could be starting colic. She recommended switching formulas, not because she thought the formula was the culprit, but because it couldn't hurt. She said that the Good Start has "comfort proteins" which are supposedly easier to digest. Isomil, though, is what they put colicky babies on, so I thought it was odd to switch her in the first place. I go back and forth about switching her back to the Isomil, but I hate to keep switching her formula. She doesn't seem to mind either formula, but I personally like the Isomil better. It doesn't smell as funky to me and the powder seems to dissolve better, but I have to do what's best for her, not me. It could be a coincidence like the doctor said and just that we happened to switch formulas the week that the baby acne appears.