The symptoms she may be psychological in origin. she is not faking this but her mind unconsciously is reacting to her treatment of her anorexia.
Anorexia Nervosa is a chronic disorder. Though this difficult to treat, it is treatable with psychotherapy and antidepressants. Research shows that most anorexics have associated depression and respond well to anitdepressants.
A consultation with a child psychiatrist may benefit you 14 year old.