Andrew Whitbread-Brown had been suffering from itchy skin for three years, especially after walks, showers and swimming.
"My skin felt like it was on fire," he said.
"I'd go for a morning walk, come home and, after my shower, my skin would be on fire for the next half hour to hour."
Mr Whitbread-Brown, of Cardiff Heights, was initially diagnosed with a water allergy, which is known as aquagenic urticaria.
He was prescribed tar soap and colloidal silver ointment.
"It was awful and didn't work," he said.
After many twists and turns in his journey to find answers, he was diagnosed a year ago with a rare blood cancer called myeloproliferative neoplasms (MPN).
Mr Whitbread-Brown shared his story to mark MPN Awareness Day on Thursday.
MPNs take three main forms - polycythaemia vera, essential thrombocythaemia and myelofibrosis.
MPN Alliance Australia spokeswoman Nathalie Cook said the conditions were often "missed, misdiagnosed or overlooked".
"MPNs are extremely rare, with fewer than six in 100,000 people diagnosed globally each year," Ms Cook said.
"But there is compelling evidence that the actual rate is much higher. Many people spend years searching for answers."
MPNs were once thought to mainly affect older adults, with an average diagnosis age in the mid-60s. Research has since shown younger people, including children, can be affected.
MPN symptoms can include itching, fatigue, inexplicable pain, headaches, dizziness, stroke, high platelet counts, as well as unusual or severe blood clots.
Delayed diagnosis increases the risk of heart attacks, blood clots, strokes and other debilitating health complications.
MPN mutations can begin decades before diagnosis. They are caused by acquired mutations in genes and are not inherited.
In Mr Whitbread-Brown's search for answers for his itchy skin, his GP referred him to a dermatologist but he didn't go because of the long waiting list.
Then a blood test showed high haemoglobin and platelets, which revealed a case of polycythaemia vera (PV), one of the three main MPN types.
"The itchy skin was a reaction to my platelets," Mr Whitbread-Brown said.
He said it was "a relief to find out what was causing my itch, but going through early treatment was difficult".
He tried drugs, including chemotherapy tablets, which he found to be toxic to his body, causing heavy fatigue and nausea.
Blood tests showed he had high liver enzymes "because of the medication".
"The doctor told me to cut back social drinking, which is hard when I'm a very social person. I have cut back on drinking a lot," he said.
He tried an amino acid called beta-alanine for itchiness, after fellow patients recommended it on a social media group.
"It's not officially recommended by anybody, but it stopped the itch," he said.
The alliance says it's not clear how these supplements work, but many MPN patients "have reported relief when using them".
Mr Whitbread-Brown said "if I knew four years ago what I could take for the itch, something simple from a health food shop, I'd have a much better standard of life than what I've had".
"I was in absolute distress because of my skin," he said.
As well as the supplements, he now takes an aspirin a day and blood pressure medication.
"When you have high haemoglobin and hematocrit, your blood is thicker. The disease increases your blood pressure because your blood is working harder," he said.
The aim of his treatment now is to stop his condition progressing.
