Why do newborns often have diarrhea when they are fed with both formula milk and breast milk?

Patient's question:

Newborn children, 15 days old, fed with Nestle instead of breast milk, have developed curdled milk and water in their stool.

Doctor's answer:

Analysis of the condition: The situation you mentioned is caused by poor gut flora.
Guidance: For this condition, I recommend taking Montmorillonite powder. Additionally, you can add Bifidobacterium bifidum to your regimen. It's also best to avoid sugar.
Doctor's inquiry: