What could cause sharp headache in top of head?

Many causes. You will nee a neurologic workup if you fall within the following categories : 1. Headache of sudden onset that persists (bleeding); 2. Hedache accompamied by physical findings such as fever, alteration of consciousness, doble vision or weakness; and 3. Headache if you have been previously healthy. In other cases of chornic headache it can be migraine or muscle. Tension headache.