With history of fainting episodes post trauma I would suggest you get a CT Scan brain (plain) done at the earliest to rule out any underlying intracranial bleed.
The commonest head injury
is intracranial hematoma
which can be precisely picked up by CT scan.
CT scan can also detect any skull fracture
Also keep a watch whether she gets episodes of severe headache
, vomiting, blurring of vision or fits.
Dont worry get the CT scan done and see a Neurosurgeon or at least a ER physician.