What is the reason for infant diarrhea?

Patient's question:

Detailed medical condition and consultation purpose: Diarrhea caused by excessive consumption of egg custard, frequent, watery. Treatment plan
Duration and persistence of this episode: 4 days
Current general condition: Feeding milk, but indigestion
Medical history: None
Previous diagnoses, treatments, and outcomes: Pepsin, Align, Oral electrolyte solution

Doctor's answer:

Apply pepsin, Lactobacillus acidophilus, and electrolyte water for treatment. Continue the treatment.