What Causes Persistent Diarrhoea Along With Vomiting, Chills And Fever?

I get recurring bouts of diarrhea every 2 1/2 weeks or so. Most of the time I also vomit but not every time. Each time I have severe shivering chills but no fever. I have had 5 episodes in the past 12 weeks. It comes and goes over a 24 hour period and then I feel pretty much back to normal.