Crystal (Harris) Hefner, wife of Playboy founder Hugh Hefner, revealed on Sunday that she’s been diagnosed with Lyme disease.
The 29-year-old model shared the news in a cautionary message posted to Instagram, warning followers to get tested for the illness if they "have EVER GONE HIKING" because it is spread by deer ticks, which are often found in the wilderness.
WATCH: Gigi Hadid Breaks Down Over How Lyme Disease Has Personally Affected Her Family
"I was diagnosed a few days ago and have a long road ahead of me," Crystal wrote, adding that she doesn't even remember getting bit by a tick at any point. "The symptoms are vast and when it has been left untreated for a long time can turn into MS, Alzheimer's, Parkinson's, Dementia and ALS."
"It is a disease so many people are living with and is becoming an epidemic," she continued, after detailing Lyme disease's many symptoms. "I always thought I was a hypochondriac. Doctors told me it was just 'stress' or 'all in my head' but I finally figured it out and you can too."
The day before Crystal shared the news and the dire warning, she seemed much happier. She posted a sexy bikini selfie to Instagram that showed off her flawless figure, in which she looked like the picture of perfect health.
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The Playboy playmate is among a number of celebrities battling Lyme disease. Real Housewives of Beverly Hills star Yolanda Hadid has long been battling the crippling illness, which two of her children, Bella and Anwar Hadid, also suffer from, as does singer Avril Lavigne.
Check out the video below to hear from the 52-year-old reality star about the toll the crippling illness has taken on her life.