I’m sorry – saw this through a notification and had to respond.
Have you suggested to the GP what he/she should be doing medically? It is so often the case that GPs will tell the educationalist what they should do, yet you know the student – and it is not their job to do this!
To be honest, I would expect the medic (GP) to refer to CAMHS for some paediatric evaluation. This would produce an assessment or diagnosis’ if it is needed – or exists.