I had a headache, stiff neck, neck pain, and vomiting for a whole week. it left for about three days and now its back. what could it be?

?Pseudotumor cerebri: You could have pseudotumor cerebri, a condition that mimics having a brain tumor. But because these are also symptoms of a real brain tumor you need to get it checked out. See a neurologist who can do the proper studies and help you get an answer.

Go to ER: A real (and very frightening) possibility is meningitis. You need to see a doctor now.