I when for a skull x-ray because i fell. was that necessary?

Yes: If the fall was significant enough to see someone about it, a skull xray can see if skull fractures may have occurred.

If severe trauma,CT: In recent years, with availability of CT scans, role of routine skull radiographs in minor neuro-trauma has been questioned. In moderate and severe head trauma, a CT scan is investigation of choice.Skull radiographs are helpful in suspected non-accidental injury,depressed skull fracture, penetrating head injury by a foreign body, or trauma in children under two years of age.