What Causes Fever, Dizziness, Headache, Vomiting With Weakness?

i am having fever ..and today is the third day
i have no cough and cold
my head is spinning when the fever is above 200 degree F
and have a slight headache always and vomiting tendency....although never vomited in the last 3 days.
I am feeling very week and cannot even stand or sit or walk for more than 10 mins.
i would like to know that whether it is a symptom of viral fever or some thing serious enough.