Is she completely formula fed? Then she might have got indigestion of the protein in formula. In breastfed babies, an imbalance of foremilk/hindmilk, often result in frothy green stools. Teething can also bring about green stools due to increased saliva.

Ma'am.. we give her formula milk..

If the potty is green in colour continously then it means baby is taking more of fore milk(watery milk which comes in the beginning its high in protein but low in fat) and less of hind milk (thick milk which comes at the end, high in fat and protein). It may lead to weight loss, so make sure you feed from one breast throughly and switch breast.