"I would really like to meet someone else with this condition," says the 48-year-old former GP from Bradford.
"I have chatted to other sufferers on the internet in Australia and one in Israel but it would help to meet someone else. The problem is that 50 per cent of those diagnosed die within the first three years of diagnosis."
Simon, who was also the crowd doctor for Bradford Bulls games, was eventually diagnosed with the very rare disorder, which can affect various parts of the body and therefore does not sit within any particular specialty – for this reason, it is sometimes called a "homeless" disease.
Simon is not alone. A recent survey by the charity Rare Disease UK (RDUK) found that 50 per cent of people with rare disesaes are repeatedly misdiagnosed. They are calling for better co-ordination for the treatment of people with rare conditions.
It took three years for Simon to be diagnosed correctly, although he believes he first started to show symptoms back in the 1980s.
Simon has something called histiocytic tissue in his brain and behind his eyes, which affects his balance, co-ordination, speech and vision.
"I was a Rugby League referee and I noticed that I started to get double-vision and then my speech would sometimes slur. Being a GP I thought I had the onset of Multiple Sclerosis and as I knew there was no real treatment I didn't seek a proper diagnosis or see a doctor."
However, his vision got so bad that he went to see a surgeon friend who'd operated on his eyes in 1999, who sent him for an MRI scan. A few days after the scan he telephoned to ask Simon to come back to see him; there were some masses behind his eyes, and it was unclear what they were.
During most of 2005 a large number of scans and investigations took place while doctors struggled to diagnose what was wrong with him.
He continued to work as a GP but on one occasion a patient, who had just had a newborn baby, refused to allow him into the house because he lost his balance as he got out of the car.
"She thought I was drunk because of my balance and slurred speech and so turned me away," says Simon, who now often wears a T-shirt supplied by the Ataxia Association stating 'I'm not Drunk, I have Ataxia.'
A few days later he had a seizure and doctors then pieced the information together and arrived at the diagnosis of Erdheim-Chester disease, one of the rarer of the rare histiocytoses – conditions where there is an abnormal increase in the number of immune cells.
"Our research into this disease in the early days was alarming, one of the papers mentioning 50 per cent mortality at three years, at this time Simon was 45," says Simon's wife Jo, a radiographer.
The seizure meant that Simon was unable to drive, a significant problem as he was still working as a GP. Treatment with interferon started in March 2006, and Simon seemed to improve. However, in February 2007, a form of chemotherapy, cyclophosphamide, was started and Simon seemed to become increasingly unwell from this point and developed chest problems. In May 2007 he had a pulmonary embolus, a blockage in a lung artery, and was put on Warfarin. "I was sent to London to see a specialist who said he had heard of the condition but had never treated it."
During this time, problems with his vision, balance, co-ordination and speech increased and he was forced to stop work.
In August 2007 his condition deteriorated rapidly and he was admitted to hospital. He was soon admitted to ICU and was on a ventilator for 10 days.
"All the doctors said that he had only a small (five per cent) chance of survival. However, slowly his condition gradually improved and on November 6 he was discharged from hospital, having spent nearly three months there," explains Jo who met Simon in 1999 on a walking holiday in the French Alps.
"I suddenly found myself retired at the age of 45 which isn't something I had planned." says Simon. "I went from seeing 20 to 40 patients a day and up to 20,000 at a Bradford Bulls match to seeing no-one other than my wife before she went out to work. That has been quite hard."
Simon is part of an online forum the ECD Global Alliance and also Rare Disease UK. RDUK's report Experiences of Rare Diseases: An Insight from Patients and Families revealed that 20 per cent of people surveyed had lived with their conditions for more than five years before receiving an accurate diagnosis.
For more than 10 per cent, diagnosis took more than 10 years.
A further 20 per cent had to see more than six doctors before securing a final diagnosis.
"Securing an accurate diagnosis is a traumatic experience for many patients affected by rare conditions and their families," said a spokesman for the charity which is calling for better co-ordination of treatment of rare diseases.
The survey found that almost one third of patients had received more than three incorrect diagnoses before being accurately diagnosed.
"Currently people affected by rare disease do not have a coherent strategy for care and support.
"Many individuals have difficulties accessing high quality care and services, in many cases due to the lack of communication and coordination of services that are sometimes already in existence.
"Due to the rarity of many conditions, health professionals often have little or no experience in supporting patients in order to find optimum care pathways which can often be difficult or impossible."
As for Simon he is spending his enforced retirement cooking, reading and listening to music – and learning to play the trumpet.
He visits a support group in Huddersfield called the Nerve Centre which gives help and advice to people with neurological disabilities.
He has recently taken delivery of a mobility scooter he jokingly calls the "Harley" which will allow him to get out of the house and see more people. It is this sense of humour which has helped Simon and Jo cope with their situation.
"You have to have a sense of humour or else you would be lost," says Simon.
"I do get very emotional now about things though. I had only ever had one day off in 18 years, In the last three years I have spent six months in hospital. It isn't much fun being on the other side of the white coat."
For more information and to see a full copy of the report visit www.raredisease.org.uk
Rare diseases affect 3.5m in UK
A RARE disease is one that affects about one in 2,000 people. Most rare diseases are genetic, and therefore are present throughout the person's entire life, even if symptoms do not immediately appear. Many rare diseases appear early in life, and about 30 per cent of children with rare diseases will die before reaching their fifth birthday. These diseases are surprisingly common – 3.5 million people in the UK live with a rare condition at some point in their lives, the equivalent to one person in 17. Rare conditions include muscular dystrophy, all childhood cancers and conditions such as Lowe Syndrome, Cockayne Syndrome and multiple endocrine neoplasia, otherwise known as MEN.