Jack Lee Hague woke his parents in distress in the early hours of 28th April 2013.
An inquest at Rotherham Coroner’s Court heard that
Steven and Lisa Hague immediately dialed 999.
Jack was then taken to Rotherham Hospital where he was given CPR, but doctors were unable to save him.
Giving evidence, Dr Marta Cohen said she believed Jack went into respiratory arrest due to a lymphatic tumour she found in his chest during a post-mortem.
She added that the tumour was so aggressive it was likely it would have taken just five weeks to grow.
Jack’s mother told the court she had taken him to the doctors several times with a chesty cough but was told he did not need treatment.
A statement from paeditrician Peter Mcfarlane, read to the court, said other symptoms were missed by doctors.
He added that although they could not be faulted, there were lessons to be learned in identifying these types of symptoms.
Coroner Mr Mark Beresford recorded a verdict of natural causes, brought on by T-cell lymphoplastic lymphoma.