I am having headache from past many days..sometimes it happens on the left side sometimes on the right side and sometimes in ma whole head..?

Possibly migraine: The classic presentation for a migraine headache is pain on one side of the head, often with a pounding quality and associated with nausea and/or sensitivity to light. That being said, there are multiple other primary headache disorders that cause lateralized pain, and these can be treated in many different ways. A neurologist can rule out dangerous possibilities and recommend treatment.

Exam and history: Too vague a question without having a thorough history and an examination. Too many variables when attempting to determine the cause of a headache. The cause, severity and location of the headache are very important.