While hormones and stress may play a role, they are only acting on the common underlying problem in ALL headaches types - an overactive brainstem. You need to understand whether or not the neck is playing a significant role in causing the overactivity in the brainstem or not. If it isn't you are wasting her time and money. If it is you need to use headache specific techniques to treat it and she should find some relief within a couple of weeks.
I would try and find a practitioner trained in the Watson Headache approach and get her assessed. If you can't locate one contact Dean or Jane at Watson Headache Clinics (google it) and they might have someone that has been trained on their database in your area (they have trained people in U.K. and elsewhere in the world).
Poke chin, supine or side lie sleeping, watching the ipad in bed and poor posture at school sitting all place the upper cervical spine at C2/3 and below in flexion. This "wedges" the C2/3 disc and causes a milder version of the same internal deformation issues without the frank outer annulus bulges. Check her spinous process of C2. How easy is it to glide with transverse pressure from each side? Does it feel rotated?
A Watson trained practitioner will examine the upper cervical spine for a direct referral to her usual headpain. That's the best place to start in my humble opinion.
Good luck.
Roger O'Toole
Director and Senior Clinician - Melbourne Headache Centre
Melbourne Headache Centre - Headache Treatment, Migraine Treatment,