A terminally ill mum with a rare autoimmune disease is "turning to stone" from the outside-in as her skin and organs slowly solidify.

Trish Rainbow-Noack, from New South Wales, was diagnosed with the terrifying disease, scleroderma, two years ago after she hadn't been feeling well and noticed her skin was hardening.

The then fit 56-year-old, who had a passion for swimming, bushwalking and the outdoors, couldn't breathe properly and was admitted to hospital. Doctors told her she was having an heart attack.

Trish Rainbow-Noack has been left robbed of her life, barely able to get out of bed some mornings. (Nine)

The condition will eventually be fatal, with the heart and lungs unable to function. (Nine)

After meeting with several physicians, a specialist eventually diagnosed her with scleroderma - a disease she had never heard of.

"It's called the disease that turns your body to stone and that's because it literally does just that - it goes hard," her daughter, Tamara, told 9news.com.au.

"The easiest way to describe the disease is the thickening and hardening of the skin.

"And after your skin turns hard, your organs mimic what your skin is doing and turn to stone as well."

Scleroderma has left her hands and feet rock hard. (Nine)

In the two years following the diagnosis, Ms Rainbow-Noack's quality of life has plummeted. The active and playful mother-of-two and grandmother-of-nine was left at the worst of times barely able to get out of bed.

Her life has been taken away from her.

"It feels as if you were to put a vacuum cleaner in a bag - the disease just sucks your skin to your bones," Ms Rainbow-Noack said.

"You can't open and close your hands because the skin is so tight.

"It's completely minimised my quality of life, I can't and never will be able to do some of the things I loved like bush walking and swimming.

"And because of that I feel like I'm limiting my family from doing things too."

Ms Rainbow-Noack has been supported by her daughters through the entire journey. (Nine)

Ms Rainbow-Noack said she was hysterical when she used the internet to learn more about the disease.

"Tears were streaming down my face," she said.

Doctors told the now 58-year-old she shouldn't expect to live more than two to five years.

"I refuse to believe this is terminal"

Scleroderma becomes fatal when the heart, lungs or kidneys harden and are no longer able to function.

But Rainbow-Noack refuses to believe she's dying.

With too much to live for, Ms Rainbow-Noack refuses to believe she is dying. (Nine)

"The future does scare me but I refuse to believe this is terminal," she said.

"It's hard for anyone to think you're dying because my family is everything to me.

"I have beautiful children and grandchildren and I want to watch them grow up, I want to be a positive part of their lives.

"There's always hope you're own of those miracle cases."

Ms Rainbow-Noack has lost almost all sensation in her hands. (Nine)

With time running out for Ms Rainbow-Noack and her condition worsening each day, she turned to a trial stem cell transplant option.

After undergoing several rounds of treatment, she's thankfully seeing some relief and has increased mobility.

"The skin is so tight"

The treatment has improved her lung function from 58 percent to 85 percent.

But doctors warn the stem cell transplant isn’t a cure and will only extend the quality and duration of her life.

"Tears were streaming down my face," she said after her diagnosis. (Nine)

"We can see a massive improvement," Tamara said.

"But if you still look at who she was before scleroderma to who she is now, it's not the same person.

"It looks like she could burst at any minute and she's turned into a frail old lady, as hard as that sounds."

The 58-year-old was full of life before her diagnosis, spending time outdoors. (Nine)

Ms Rainbow-Noack said despite life for her and her husband completely changing, he's stood by her side and reminds her everyday how much he loves her.

"He never complains. He's sat by my bedside and took time off work.

"He reassures me of his love on a daily basis...but I keep reminding him, he's got a good wife," she laughed.

Her husband has stuck by her side through the entire journey and reminds her of his love every day. (Nine)

Tamara, her father and her husband are now on a mission to make the horrifying disease more known and raise money for a cure.

"It looks like she could burst at any minute"

They'll be going on a massive 585km walk from Port Macquarie to Campbelltown over a two week period for their mum, ending on June 29, which is World Scleroderma Day.

Walking more than a marathon a day, they'll trek down the east coast of New South Wales with their mum following in a support vehicle.

"It feels as if you were to put a vacuum cleaner in a bag - the disease just sucks your skin to your bones," she said. (Nine)

"I am nervous and we have been training solid but there is nothing you can do to prepare you for a walk like this," Tamara said.

"But it's my mum that keeps us going, even though we’re in pain, what we’re feeling is nothing compared to what she's feeling.

"Even though I don't have the disease, I just want to try and make their lives better and let them know they aren't alone."

It's estimated there are more than 5000 people in Australia are living with scleroderma. (Nine)

It's estimated there are more than 5000 people in Australia living with scleroderma.

The disease, which is not hereditary and usually develops between 40 and 60 years old, affects women at least three times more than men.

The family has already raised more than $40,000 for scleroderma research and is dedicated to keep fighting until there is a cure.

(Nine)

"My mum has the kindest of hearts," Tamara said.

"She would go above and beyond to help anyone out even though she's so sick.

The family has already raised more than $40,000 for scleroderma research. (Nine)