welcome to hcm
thanks for the query
if its greasy stool which is very foul smelling then consult the pediatrician
most cases go by there own without treatment. just try to give enough fluids to prevent dehydration
it may be be infective one or due to food poisoning
it may be due to some medications also.
so better to consult a pediatrician
and get evaluated.
take small and light foods. take more amount of fluid.