Medical specialists have investigated epilepsy, thyroid disease, testicular cancer and auto-immune disease.
But every blood test, scan and examination came back negative.
"I try to be as healthy as possible," Hiscock says.
"I exercise, eat organic food, I don't drink at all, don't smoke or take any kind of drugs."
Fed up with being sick, and accused of being a hypochondriac, he began researching his symptoms in medical journals and on the internet.
Hiscock believes he is among the small percentage of people who are hypersensitive to water fluoridation.
Hiscock no longer drinks water from the city's tap. Instead, he travels to Petone where the artesian water supply is non-fluoridated. "There is large reservoir of crystal-clear water in Petone and Lower Hutt, so my wife and I fill up 20-litre bottles each week.
"Since drinking and cooking with exclusively fluoride-free water, almost all of my major symptoms have slowly gone away."