Recently I wrote a guest post for Annabel Karmel that features on her website and its all about managing lactose intolerance in babies.
Lactose intolerance sometimes gets confused for cows milk protein allergy and vice versa. if your baby seems to not tolerate formula or breastmilk but your not sure what it could be, you can read about cows milk protein allergy here too.
Do make an appointment to see your GP though if you are concerned and if it does turn out to be a problem with milk, ask for a referral to see a paediatric dietitian. A paediatric dietitian will guide you through a nutritious milk free weaning diet for your baby and a balanced milk free diet for breastfeeding too. They will also support you through the reintroduction phase sometimes called the milk ladder.