Breast fed my baby for 6 months and after trying formula milk had an unsettled baby waking up all night, also teething at the same time so initially thought it was teething. Went to the doctors and he suspected milk allergy especially as babies father has it(into adult life). Now on the allergy milk with the proteins broken down and baby back to be right as rain. For anyone else finding all hell lets loose after trying some formula milk after breast feeding, definitely suspect milk allergy.