Thank you for your query,
Your child seems to have a mild diarrhea
due to a virus most probably.
You can give sips of oral rehydration solutions like Pedialyte
, coconut water, and lemon water.
The lethargy may be due to some dehydration
Monitor her hydration by her activity, urine output, and skin turgor.
Consult your Pediatrician
for the examination of the child and for specific treatment.
Hope I have answered your query, if you have any clarification please let me know.