Lyndsi Johnson, 28, regularly faints up to ten times a day and can't stand for more than three minutes at a time without fainting.
The former navy mechanic started suffering from the strange syndrome in October 2015, when she experienced intense abdominal and back pain.
As the years went on, her symptoms worsened and she began experiencing projectile vomiting and fainting up to ten times a day, with no explanation from doctors.
In 2018, she was medically discharged from the military due to her unexplained illness.
Lyndsi was even hospitalised several times over the past few years, but she was told it was probably her anxiety causing her symptoms.
Things got "really scary" in 2020, when Lyndsi passed out in an elevator on the way to a hospital appointment.
“My fainting got worse from there," she recalled.
"I was passing out everywhere - I would be shopping at the supermarket and I had to sit down because I felt faint or at the gym. I’ve even passed out after my dog has barked.”
Eventually, in February 2022, Lyndsi was diagnosed with postural tachycardia syndrome (PoTS) - an abnormal increase in heart rate that occurs after sitting up or standing- which Lyndsi also refers to as an 'allergy to gravity'.
“I was so thankful to finally know what was wrong with me so I could be treated," she said.
Although she's on betablockers for the 'allergy', Lyndsi still faints up to three times a day, and has to rely on her husband James as her caregiver.
“I still can’t really do anything," she admitted.
“It’s really debilitating - I can’t do chores and James has to cook, clean and help me shower and wash myself.
“I’ve gone weeks without brushing my teeth because it just makes me feel awful.
“If I make a meal for James and I, then I’ll be in bed unable to anything for the next three days.”
Lyndsi is now trying her best to adapt to the illness and make the most of her situation.
She and her husband are now hoping to move from their flat to a house so she can spend time outside.
“If I’m lying down I feel fine but as soon as I stand up I’m dizzy and faint,” she said.
“I’ve really had to adapt to this new life and come to terms with it. I use mobility aids and that really helps for me.
“I’m grateful for what I have and I’m still able to study music business which is amazing.
“The rug has been ripped from under my feet - I’ve gone to super active to having to lay down all day.
"I can't do a lot of what I used to be able to but I've come to terms with that now."