for more than 14 days is called persistant diarrhoea and should be investigated.
Stool smelling fishy is usually indicative of vibrio cholera
diarrhoea which needs to be treated.
But your child seems to be fine clinically which is a good sign.My advice would be to try out a probiotic
and zinc preparation for some days and go for a stool test
if possible. Kindly avoid milk, fruits and fruit juices,wheat products for time being. If her loose stools persist beyond 14 days please consult a specialist if possible.
Wishing her a speedy recovery.
Have a nice day