(migraines or otherwise) are known to persist for up to 3 years after a head injury
considered significant enough to be classified as either a traumatic brain injury
. If the "hit" to the back of your head did not really daze you or cause you to become confused or disoriented in any way then, it is less likely that it could be classifiable as a true concussion. But if the strike to the head did cause you to become dazed, confused, disoriented, or otherwise, "out of it" to any extent then, headaches may persist for quite some time.