Colette Tait and her son Alexander endured unexplained symptoms for years before finally being diagnosed with a form of muscular dystrophy.
The mum, aged 44, was being investigated by dental specialists for a problem with her jaw, while 15-year-old Alex was bullied at school for being overweight, caused by mobility problems.
But six years ago relatives got in touch to say they had been diagnosed with the genetic condition myotonic dystrophy - and tests confirmed the same illness in Colette and her son.
The disorder causes muscles to weaken, stiffen and waste over time, leading to increasing disability.
Colette, from Lowedges, says her symptoms could be eased with help from a specialist neuromuscular physiotherapist - but that no such role covering Sheffield exists.
According to the Muscular Dystrophy Campaign charity, hundreds of families in the city are ‘missing out’, despite funding being announced for two physiotherapists in 2012.
One was hired in West Yorkshire, but the charity says little progress has been made here since the former Yorkshire and Humber Specialised Commissioning Group became part of a larger NHS organisation.
Colette said physiotherapy would keep her and Alex mobile, as well as slowing down the progression of their illnesses.
“You need a properly trained physiotherapist so they don’t make any of your symptoms worse,” she said.
“The condition makes you feel like your head is too heavy to carry. I walk with a stick but have to use a scooter if I’m going longer distances.
“Alex was overweight when he was younger and got bullied in school. He couldn’t run, but obviously he didn’t know why.”
Alex, a pupil at Meadowhead School, is now a budding motor racer.
“He just wants to forget what he’s got and he overcomes it - I’m really proud of him,” Colette added.
The charity estimates that there are more than 620 people with neuromuscular conditions in Sheffield.
Specialist physiotherapists give advice on stretches, activities and exercises, as well as helping colleagues to treat patients’ specific needs.
An NHS England spokeswoman said the decision to fund the new role was taken by local Primary Care Trusts before they were abolished last April, but that a business case was now being developed.
“NHS England recognises that muscular dystrophy services are vitally important and we are actively supporting the Muscular Dystrophy Campaign’s programme of work,” she said.