Dear Parent, Please mention some details about the issue.
Loose stools::: duration/ how many times a day/ color/ consistency/ quantity
What about her weight gain/ food intake/ urine output !!
Is the any other associated problem like fever, vomiting, urine problems etc...
And you said 1 month so if it is continue more than 14 days than it is persistent diarrhea
Next Steps
If above history is suggestive than we can initially do two simple tests
Stool Routine and For Reducing substance
Urine Routine and Micro