HI, thanks for using healthcare magic
Frequent watery stool is normally indicative of infective diarrhoea
. It is treated with rest and enough fluids to prevent dehydration
Extreme foul smelling stool can also occur with melena stools which are black, tar like stools that occur when there is a bleed in the stomach or intestine.
Since it has been going on for 2 weeks, it may be best to take her to a doctor or have her doctor do a home visit if it would be too difficult for you to get her to the office.
I hope this helps