'Without the web, I'd still be searching for a diagnosis'
Amy Garton-Hughes is 22, but the size of an eight-year-old.
She has Cockayne Syndrome - a rare genetic disorder which degenerates the body and shortens young lives.
This cruel illness has taken away Amy's balance, her speech is deteriorating and she has signs of dementia.
But she still enjoys a busy life - listing swimming, bowling and seeing friends as her hobbies.
Jayne Hughes, from Merseyside, spent years trying to identify her daughter's illness. Doctors were mystified and library books gave no answers.
But online searches eventually did - yielding pictures of other children with the same distinctive sunken eyes and pixie-like faces.
Jayne said: "When I found Cockayne Syndrome on the internet, there were a couple of photos of different children that all looked like her.
"So I printed them off and when my dad came round, I said 'have a look at this'. He asked when I'd taken that picture of Amy. I said 'actually it's not Amy'.
"It was at that point when I thought - this is it, that's definitely what she's got."
Jayne Hughes jokes that she only recently learnt to cut and paste. But she has found the internet invaluable.
Her family's website, Amy and Friends, supports 1,500 other young people around the world who are affected by Cockayne Syndrome.
Jayne added: "If it wasn't for the internet, I'd still be searching. Trying to find out what was wrong with Amy was like an obsession.
"I couldn't settle or sleep and I couldn't look after my other children properly. Without the internet I'd be lost."
But for others, the world of web forums and online symptom checkers can be a minefield.
At a mental health centre, run by Imperial College Healthcare in London, community psychiatrists treat people who have "cyberchondria" - health anxiety fuelled by the internet.
Professor Peter Tyrer said: "Cyberchondria is just being recognised as an extremely important part of this. We find that approximately four out of five of our patients with health anxiety spend literally hours on the internet."
He says cyberchondria, which gives sufferers a deep fear of diseases, is on the rise. His research on this has been published in The Lancet.
There is good news - it can be treated effectively with simple therapy.
Prof Tyrer said: "One of the first things we do in treatment is we tell them to stop browsing the internet.
"And we ask them to keep diaries, which demonstrate very clearly that when they look at the internet, their anxiety increases.
"The trouble is the internet contains all the knowledge you need to know - but it doesn't have any judgement associated with it."
Backlash from doctors
Technology does of course present new opportunities for solving old problems.
Dr Christian Jessen - a GP, TV presenter and voracious user of Twitter - estimates about two-thirds of his 30,000 tweets have been answers to people's health questions.
One recent example was someone who was struggling to get an appointment to have their ears syringed.
Dr Jessen said: "I advised them to use olive oil as drops. Olive oil is anti-bacterial, antiseptic and softening - they may not need their ears syringing after using that."
He has some ground rules: he always retweets the original question, and he refuses to offer medical opinion on photos that people send him.
He sees this as a modern and succinct way of helping people.
Dr Jessen added: "When I started doing this, there was a backlash. Doctors hated me doing it. They said I shouldn't interact with people I'd never seen before and answer medical questions.
"But it's no different to being at a party, when you announce you're a doctor. The first thing people do is launch into a long medical story and ask for advice. It's exactly the same thing."
'Horrified' cancer patient
Another respected website, HealthTalkOnline, focuses on patients' stories. It is carefully researched and curated by academics.
In its seventieth collection of stories, people talk frankly about being on anti-depressants.
Stuart Jessup, an engineer turned teacher, was recruited by Twitter to take part in the work.
He has walked the British coastline to raise awareness about depression. At the launch, he jokes about how online forums for depressed people are best avoided.
He said: "Depression is a cycle of negative thinking. So put lots of people who are stuck in negative thinking together and moderate it - it's dangerous!"
Professor Sue Ziebland, from Oxford University, has spent 15 years examining how patients use the internet - including people with cancer.
She said: "One of the men we interviewed went to his local library to go online and look for information about local support groups.
"Almost the first thing he found, on one of the voluntary society websites for that particular cancer, was the very distressing five-year survival rate.
"He was horrified. He shut down the computer and ran out of the library.
"The information he found was entirely accurate - but perhaps it shouldn't be on the front page. It's about signposting. "
After sometimes seeing the internet as a threat in its early days, Prof Ziebland says doctors now routinely discuss it as a resource with patients during consultations.
It has become an everyday part of medical conversation.