Has she been evaluated for a possible TMJ (tempomandibular jaw joint) problem?
The symptoms you describe are classic symptoms of tension in the facial muscles. I have been dealing with a severe TMJ (temporomandibular – jaw joint) disorder for all of my adult life (I'm 61). So I am very familiar with the muscles in the head/neck/jaw and how they feel when they are tight and tense.
Stress and anxiety cause us to tighten our muscles. The main chewing muscle, the masseter, is the muscle in your cheeks. It is the strongest muscle in the body by weight to enable you to chew food. It may be that she is unconsciously clenching her teeth, even during sleep, which will tighten and stress the muscles and cause discomfort and aching in in the face and head.
Has she had any recent dental work or change in her teeth? Any life events causing stress?
If nothing else has been found, it would be worth checking into the possibility of a TMJ issue. The TMJ association is a good source of reliable information.http://www.tmj.org