I have had diarrhoea since about 3 this morning and i have to go out tonight , is there anything i can do to get rid of it asap?

Bowel rest helps: The GI tract will 'complain' if it is not ready to be used -as in recovering from gastroenteritis. If possible, I recommend to limit the intake of food/water for a short period of time-see if that helps. There's the risk of getting dehydrated though, so I would only recommend that for a few hours. It's best to manage the symptoms at home, near a bathroom. There is imodium, but there's side effects