Change your babys diaper often. The baby can not adapt to it. It could just be the milk is too rich but you could try replacing her milk with lacto free milk from supermarket in milk isle and see if the diarrhoea stops She will need a lactose free formula full time if lactose intolerant for the nutrients but trying this should give you an idea in the short term.
Also if her diarrhea continues or worsens talk to your health care professional.
If your baby is having diarrhea abdominal pains blood in the poop or bloating you may already be working on changing your babys formula. If he thinks the diarrhea is due to cows milk protein allergy he may recommend Nutramigen A with LGG a hypoallergenic formula has been clinically proven to reduce colic due to cows milk protein allergy quickly often within 48 hours 12. I am course freaked out that hey may have a milk allergy or something. Stools come out watery and too frequently.