Hi My Child Is Now 1yr 11months Old. From Last

Hi my child is now 1yr 11months old. From last friday she's having fever with loose motion. (Just like watery & smelling). After giving prescribed medicines now she's not having fever any more. Now she's doing loo better than earlier but still its seems to be not soo good. Is it better to check a stool sample whether it has something wrong? What should i need to give her to eat thesedays? I'm from Sri Lanka