But after years of searching for answers - and being diagnosed with everything from lupus to fibromyalgia - a specialist took one look at her hardened skin and recognised scleroderma.

The name of the autoimmune disease literally means 'hard skin' and one of the hallmarks of it is the thickening or hardening of the skin.

In its worst form it affects the connective tissue throughout the body, causing serious damage to internal organs.

"I've been told my condition is terminal unless its progression can be stopped," Mrs Rainbow-Noack, 60, said.

"I was given a time limit on my life expectancy of two to five years - that was two years ago.

"I was diagnosed in 2016 and it's getting progressively worse. I'm unable to walk more than a few steps, my hands are curled inwards and I'm unable to grasp things, and I'm tired and hurting all over.

"It affects my lungs, heart and other internal organs - causing spasms and making it difficult to breathe.

"Your body just gets stiffer and stiffer - it's made me old very quickly. Over time, you slowly start turning to stone."

The mother-of-two admits that any hope for a cure is dimming for her, yet she knows her family will never give up on her.

Her husband of nearly 40 years, Stephen; along with her daughter Tamara Kennedy and husband Andrew; have already raised $50,000 for vital research into the condition at the Garvan Institute of Medical Research.

Next month, the trio will embark on another fundraising trek - spanning 200km from the Shoalhaven to the Illawarra and on to western Sydney.

Mrs Kennedy said it's been devastating to watch her mum once "full of energy, the life of the party, the backbone for our family" give up work and the many activities she loved, like fishing and hiking.

"I have watched my mum change from an independent, confident, outgoing person, to a person who wants to do all these things but physically her body just doesn't let her, it's like she is trapped in the body of a 90-year-old," she said.

"You can see the constant battle she has with herself every day, it's torture watching her go through this, I wish every night that I can make her better, make her life that little bit easier, to take the pain away for her.

"Having a shower is a struggle, she can't walk up the stairs of her beautiful home, just getting dressed each day has her out of breath."

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The walk kicks off on February 27 from Greenwell Point, with the first stop in Kiama, then Thirlmere, and ending in Smithfield. All funds raised will go to Scleroderma NSW.

"More than 5000 Australians have scleroderma and there's some very young people, and children, being diagnosed which is heartbreaking," Mrs Rainbow-Noack said.

"While no-one wants to give up hope, I don't think I'll see a cure in my lifetime. My only hope is that research will one day lead to a cure or better treatment so that others don't have to go through the agony I do."

The family shares their journey on their Facebook page '500,000 Steps for Scleroderma'.