Hi , I'm Dr Suresh K Yadav M D (paediatrics) ,I have gone through your question and understand your concerns,
Nor-
metrogyl is most misused medicine for 
diarrhea , it is not recommended to use with out a prescription, more important is use of ORS and zinc to take care of 
dehydration  and build gastrointestinal immunity . Most loose stools are viral or self limited bacterial infection of  of 3- 7 days duration , you need to take care of dehydration during this time and keep a watch on dangerous signs like dullness, irritability , lees urine, 
high fever, very large or very frequent stools , presence of 
blood in stool or if otherwise child appears sick . In presence of any such signs you need to consult your health care provider urgently . Passage of greenish stool in absence of blood in stools , it not a reason of concern . 
Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions.
Take care.
Thanks.