Thanks for choosing HealthcareMagic forum.
The most common cause of diarrhoea
in children is viral only. After every bout of diarrhoea, the weight gain of child goes back by around 15 days. in your case it was a persistent diarrhea
for 45 days. So, now it will take at least two months for your child to recover from the weakness caused by the illness.
Dr. Rakhi Tayal