A MRI scan revealed the truth.
"You could say I was unwell for nine years before finally being diagnosed," she said.
But Chamberlain resolved to not let it beat her. "The night I was diagnosed I got my hair done as planned," she said.
"Then on Saturday I went to the races with my friends - though I was using crutches for balance."
Now Chamberlain is taking on a different sort of challenge. She's training to ride Bike the Bridge on Sunday, November 10. It's a once-a-year opportunity to cycle across the Auckland Harbour Bridge and is a fundraiser for MS Auckland.
"I just want to prove that I can still do things and I want to raise more awareness of exactly what MS is."
She'll be riding the 50km option in November. For many cyclists that's a relatively straightforward goal, but for Chamberlain it's not so easy.
"MS means that I have to think twice about what I can and can't do. It's easier to think you can still go on as normal and most the time you can but sometimes I have to step back and let myself recover."
Issues with arm and leg strength, vision and fatigue are some of the symptoms of MS that make any exercise a challenge.
"Unfortunately I've had a knee injury, so luckily cycling is the one thing I'm allowed to do to help improve that.
"Getting up early can also be a problem, but getting into the routine helps and I just really want to complete the 50ks and cross the finish line."
Bike the Bridge was first run in 2011 and was a big success.
Organiser Callum McNair has fine-tuned the event for this year and promises a great experience for all those who take part.
He's got a very personal reason for making the Bike the Bridge's fundraising for the Multiple Sclerosis Auckland Region Trust a success.
"My wife has MS so I know just how good these guys and gals are at supporting families like mine," said McNair.
"They have meagre resources and virtually no government funding and they still have the best fieldworkers and the best support systems a family like mine could wish for."
Chamberlain agreed and had some simple advice for other people in her situation on how to cope.
"Smile," she said. "I've had a lot of people say that they're amazed I didn't break down every five minutes when I was first diagnosed but I've just tried to stay positive and focused and be open about it."
A great support network also helps. "Just remember that what works for one person won't always work for you so be prepared to try other things. I do still have my break-down moments, but I have them when no one else is around.
"I'm taking each day as it comes, and, hey, maybe next year, I'll do the full 115km Bike the Bridge ride."
Follow Chamberlain's journey and donate: bikethebridge.everydayhero.com/nz/sjcnz