I find that, when I get a severe headache, it often leads to nausea, as well. Did the headache start first, and then the nausea, or did all of your symptoms start at the same time?
Ordinarily, I would advise that you take some aspirin or other pain medication, but it sounds like you would have trouble keeping those in your stomach. You might try the liquid form of, say, acetaminophen (Tylenol), since the liquids sometimes are easier to tolerate.
It also sounds like you have a fever, which is all the more reason to get a fever reducer, such as acetaminophen, into your system.
If any of these symptoms persist, please see a doctor. It could be a case of the flu. But, as harshini indicates, it could be something more serious.
Hope you feel better...
gastric problem might be d reason..consult gastroenterologist..