The Canberra man, now 45, was suddenly afflicted with lingering dizziness, brain fog and overwhelming fatigue.
It would take nearly two years, dozens of medical appointments and trips interstate before he was diagnosed with two neurological conditions.
Postural orthostatic tachycardia syndrome (POTS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are complex, poorly understood and affect thousands of Australians.
"I think a lot of people get despondent with how long it takes," he told AAP.
"I actually count myself as one of the lucky people."
Mr Dunn's experience is consistent with the findings of Australia's first national survey of people affected by neurological conditions.
More than two million Australians live with neurological conditions - diseases of the nervous system including motor neurone disease and dementia.
The Neurological Alliance Australia survey, published on Wednesday, canvassed 2805 such Australians, identifying widespread barriers to care.
More than half the respondents (51 per cent), said they had difficulty accessing care, while 30 per cent waited over four years for a diagnosis.
Fewer than four in 10 people (39 per cent) described their care as co-ordinated and just nine per cent said they felt fully supported by their healthcare team.
Rohan Greenland, chair of the peak body, said wait times and cost barriers can have serious implications for people with long-term health conditions.
"A delay in one part of the system can severely impact their health, independence, employment, family and future care needs," he said.
It's a challenge Mr Dunn, who eventually had to give up his career after working reduced hours, knows firsthand.
"For people with limited and in some cases unpredictable energy ... to navigate this fragmented system health system that we have is really overwhelming," he said.
The findings added to a growing body of evidence that treatment for long-term, complex health conditions is falling short, the NAA said.
It is calling for the federal government to develop a national action plan for neurological conditions, supported by state and territory plans.
Priorities include earlier diagnosis, better access to specialist care, more co-ordinated services and increased research funding.
For Mr Dunn, who now volunteers in the disability sector, medical education, more research and broader access to care were front of mind.
"There are barriers to support at every stage of the illness life cycle," he said.
"It's having such a huge impact on the health and well-being of so many Australians with neurological conditions, but then also on all the people who look after them."
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