I suspect just giving the doctor's contact details will not be enough
You're quite right - no one will make enquiries.
Other factors that might be relevant:
• the exact dates from start to finish
• whether grandfather was close by or a long way away
• whether the school can confirm that your son seemed withdrawn, whether there is evidence that his school work was affected.
An appeal panel has the opportunity to ask questions, and to try and elicit the facts.
With a review panel it's entirely up to you anticipate what might be required and to submit all relevant information.