Diarrhoea can sometimes persist for a while after a bout of stomach flu or food poisoning. The most important thing to do is to prevent dehydration, and replace your electrolytes as necessary.
Usually stomach flu is self-limiting, but as your symptoms have gone on for more than 5 days, do watch out for other symptoms such as fever - if so, your doctor may want to perform a stool culture.
If your diarrhoea (defined as >3 loose stools per 24 hrs) persists for longer than 4 weeks, then this is termed "chronic diarrhoea", and your doctor may need to do further investigations.
