She should get a MRI and CT scan of head and neck and for the added dizziness, even an MRI of the sinus. I of course am no doctor but have had many tests such as these and was reassured when I found the true cause.
Just knowing what it is can ease the anxiety, albeit, not the pain.
But once you find out it isn't something deadly, you can live through the pain knowing that "this too, shall pass".
Let us know what she finds out. If it is related to muscle, bone or pinched nerves, physical therapy is a wonderful way to go. Save the heavy meds for the worst of times.
God bless and help your friend find the answer.