Callie Blackwell's online blog has documented the journey of Deryn's illness from the start.

To the thousands of followers the mother-of-two found a way to tell the world the intimate details of what's happening to her son.

Readers have laughed, cried, wanted to help and have been left speechless.

But Mrs Blackwell, a former bouncer who gave up her job to look after Deryn, has revealed once she has written the harrowing and heartbreaking posts – she cannot read them back.

'I know I can come across quite cold when I write my blog,' she said.

'But it's difficult. If I feel every emotion I would have had a break-down by now, you have to take yourself away from it.'

Deryn's foundation Do Everything has been propelled by his mother's energy and enthusiasm to drum up support for her son and knowledge about his conditions.

Using the social media websites Facebook and Twitter friends and family of the Blackwells have been kept regularly informed on the teenager's progress with photographs and words.

Mrs Blackwell said: 'Deryn has been shown that life is worth living.

'As each week goes on the more he feels better, the more he is looking forward to living.

'Now it's an exciting time. We feel for the first time in a long time that there's some level of certainty. Now we can look