A devastated family have told of the extreme shock of learning their ‘sporty’ 15 year-old has inoperable, aggressive brain cancer – with the only warning sign striking hours before his diagnosis.

Callum Stone, 15, from Chelmsford, Essex, was hit by a debilitating migraine one January morning during the school day.

When mother, Sarah, 41, and step-father, Mark, 42, came to collect him, they realised that he was struggling to speak.

They took him straight to A&E and, terrifyingly, the teenager suffered three major seizures in the car on the way to the hospital.

Once the family arrived at Broomfield Hospital in Chelmsford, doctors admitted Callum for a week in order to carry out a series of test including CT and MRI scans.

Results showed some inflammation in his brain, which doctos put down to a viral infection.

Callum was later discharged with anti-seizure medication, as the medic in charge said she believed his health was ‘back to normal’.

However, the teenager was referred to Great Ormond Street Hospital in London for further monitoring, where doctors carried out a more detailed MRI scan.

Callum Stone, 15, was a perfectly healthy and active 15 year-old when doctors discovered a tumour inside his brain that was growing ‘like a cobweb’

Devastatingly, the images revealed a ‘large tumour’ in Callum’s brain.

He underwent a biopsy on the mass on February 5 and on February 11, the family were informed he had a diffuse grade four glioma – a type of aggressive cancerous tumour that starts in the brain.

Grade four gliomas are the fasted-growing type and only around five to 10 per cent of sufferers survive longer than five years after their diagnosis.

Speaking of the diagnosis, Sarah said: ‘It was shattering.

‘In a matter of hours, our world has just completely been thrown upside down but a few months ago, we were just a normal family.’

Worse still, the family were informed that the tumour was inoperable, and growing like a ‘cobweb’.

‘Doctors would need to take away too much of the healthy cells,’ Sarah explained. ‘It’s quite hard to explain something like that to a child and his brother.’

Mark added Callum was more concerned about his family members when they delivered the news, saying he ‘smiled and hugged us’.

Despite his illness, Callum is getting stuck into exercise and healthy eating to keep himself in the best shape as possible during his treatment

Initial MRI scans failed to spot the tumour, and doctors sent him home with anti-seizure medication telling him everything ‘looks normal’.

On February 14, the family travelled to University College Hospital in London where Callum later received six weeks of daily radiotherapy.

He completed the course on April 4 and he will receive an MRI scan on May 5 to see how the tumour has responded to the treatment.

‘He’s gone from being a boy who has never been sick to taking so many different tablets and being in hospital,’ Sarah said.

Callum has been concentrating on his fitness regime and his diet to remain healthy, with Mark saying he has been going back to the gym over the last few weeks.

‘He’s been very good, he’s been exercising and keeping in touch with his friends – he’s doing as well as you could be,’ Sarah added.

‘There are times away from the kids where you didn’t think you could ever cry so hard but as soon as you see them, you want to start planning things, going out and seeing friends, family.

‘They make it easier to get through the days.’

The family have launched a GoFundMe page to raise money to explore alternative cancer treatments abroad.

Callum will start ongoing chemotherapy treatment in tablet form next month, but Sarah said ‘for his type of tumour, there are no other treatment options for him on the NHS’.

The family are starting to look for options that may be available abroad, such as a clinic in Germany, and clinical trials in San Francisco.