Thank you for your query.
I can understand your concern. As no definite conclusion has been drawn by the treating doctor and the symptoms described by you, I suggest that the following investigations be done to rule out various possible causes:
1. Stool routine examination
of the whole abdomen
3. Neurological examination.
If the above come out to be normal then a psychological assessment should be done. Enquiry from her school may throw some light on any problem that may have arisen there between the friends or with any particular teacher.
I hope I have answered your query to your satisfaction.
Wishing your daughter an early recovery.