Has my little one got allergies or is it normal

So my little one is one day away from two weeks old and dairy allergies run in the family I myself had it as a child but out grew it but even as an adult too much milk or chocolate can make me stuffy my wee nephew has it even the slightest bit of dairy and he has diarrhoea for weeks sometimes I don’t know about myself how it started but for my nephew they could tell by his poops he had it he wasn’t spewy baby my little ones poos have became mucusy and green with a ring of yellow one of her nappies today was also extremely runny iv spoken with my midwife and she said not to worry as she’s not being sick but to keep an eye on it what is everyone’s thoughts who have experienced a child with dairy allergies

Many thanks