YA, I agree ...it could be a sinus infection ,a sinusitis more specifically .You should see a ENT SPECIALIST and even a MRI investigation which should show such an infection .
What kind of specialist did your friend go see?
She finally saw a doctor in New Mexico who found an infected pollop somehow in her jaw bone. She suffered for three years with doctors telling her that there was nothing wrong. Once the massive infection was removed from the bone in her cheek she was fine and is still fine. By the way she was living in Chicago at the time and traveled to New Mexico to see a specialist on her own.