Deni.....this problem sounds viral in origin, probably one of the adeno viruses. Drink plenty of fluid, or suck on an ice cube. If you feel like eating, then do so, whatever you fancy.
As cherry says, 4 days is a long time and dehydration may well become a problem. Nip the skin of your arm and if it does not retract straight away,then you may well be dehydrate.
I am not a fan of NHS Direct.
My advice, is to call your GP today, stressing the length of time that you have been ill.