Hello There. I'm A Little Concerned, I Have Had Diahrrea

Hello there. I'm a little concerned, I have had diahrrea the past 4 days. And it hasn't gone. The first day I had diarrhoea, felt sick, head ache, drowsy, very tired. And had a temperature. Then by the second day, everything else had gone but the diahrrea still remained, same for the third and fourth day and now I'm curious as to why it hasn't subsided yet. Other than the diahrrea I feel perfectly normal now. Any ideas? What could this be?