I made the mistake of giving luke cow and gate hungry baby when he was 3/4 weeks old as he was feeding so much. It was a big mistake, he cried for 5 weeks and i mean really cried for the whole day, wouldnt feed proparly and during and after feeds pulled his legs up to his tummy whilst screaming. Our health visitor thought he was lactose intolerent and Our doctor thought it was reflux or colic, and said we just had to live with it. I then realised that the crying started about the time of his milk changing so researched it and found out that hungry baby milk, although says from birth on the carton is not recommended until at least 3 months as it is so hard on babies tummys. We changed him back to stage one, and the crying decreased and he became a lot happier x