Soft stool consistency in a number greater than 2 stools.
Sudden onset of a minimum of 2 stools with a soft content.
If you have at least 2 diarrhea stools of soft consistency for one day you need not be alarmed, there can be multiple factors, but most likely it is a food-borne.
But if these stools are accompanied by vomiting,temperature or visual disturbance then you should contact a physician immediately.
If you've recently returned from a foreign country then read about traveler's diarrhea.