In May, after returning from a holiday of a lifetime in Cancun, New York and San Francisco, Nina found out that four of the six main veins in her right leg were blocked with blood clots.
"It was a complete surprise as I am fit and healthy and not overweight," she told the Daily Mail.
"My body is walking, ticking time bomb right now. So I need to have a healthy mind and healthy body," Nina said.
Nina, who first appeared on TV screens as a contestant from Sam Wood's season of The Bachelor, said that she has had to drastically change her lifestyle to ensure that she doesn't dislodge the clot, which could be fatal.
A blood clot that dislodges and begins moving through the bloodstream can be harmful if it gets stuck in the lungs.
"I can't wear high heels, I can't drink. I can't do anything where there is any risk of head knocks," she said.
"If I knock my head I can get internal brain bleeding."
Speaking about her experience about reality TV in May, Nina claimed that the women were forced to live in 'asylum-style' accommodation and shared just one washing machine between them during an interview on the Confessions of a Twenty Something Train Wreck podcast.
She also revealed that filming was essentially a full-time job, with the women expected to be on camera ‘five days a week’ and rose ceremonies often lasting until 3am.
"We filmed five days per week with a two-day break, which wasn't always a Saturday or Sunday but it was always two consecutive days," Nina said.
She also spoke about the living arrangements during The Bachelor's third season.
"So if you think of, like, school camp crossed with a psychiatric asylum, that's what it feels like!" she admitted of the Hunter’s Hill mansion.