Bella Hadid pens emotional note about her mother's Lyme disease

Bella Hadid has posted an emotional post to her Instagram page about her mother's battle with Lyme disease.

The 19-year-old supermodel, who recently walked for Misha Collection at Mercedes Benz Fashion Week Australia, took to her social media account to upload a picture of her mother, Yolanda Foster's new book called Believe Me: My Battle With the Invisible Disability of Lyme Disease where she details her struggles dealing with the "invisible" condition.

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The young model, who was announced as the new face of Givenchy and also suffers from Lyme disease, recalled the time she woke up at 3am to bring her mother to hospital and get a shot and how she would cry herself to sleep over Yolanda's pain.

"I am also SO proud of my mom @yolanda.hadid today and everyday," the post started.

"This book marks such an incredible day for you. I have seen you in bed, struggling for the past 5 years of our lives, thinking to myself 'why would this happen to such an angel?' I would cry to myself knowing that there was nothing I could do to help and that there were people going against you and what you are/were going through.

Bella went on to chronicle her own struggles throughout her mother's disease, which she was diagnosed with in 2012.

"Incidents where you would be so sick, not being able to move your bones/body, and I would have to drive you to the hospital at 3 am so I could see you get a shot of something just like every other day you would have to do treatment.

"You have been in more doctors labs and testing rooms every SINGLE day, then I have ever seen in my life... To find a CURE for people around the world.

"I have been struggling with Lyme and other co-infections for the past two years which has debilitated me from riding my horses, going to school, and struggling with work which are all the things I am so passionate about. you are the only person that would believe me and understand what I was going through.

"This book shows Kids and adults with Lyme across the world that you are not alone and we believe you! If you would like to read about @yolanda.hadid journey 'Believe Me' is available for preorder on Amazon. I love you mommy."

Real Housewives of Los Angeles mother-of-three Yolanda has previoulsy spoken out about her kids Gigi Hadid, Bella Hadid and Anwar Hadid and how they kept her alive throughout her illness.

"My children is what kept me alive," she told Dr. Oz in March.

"I remember just waiting for them to get out of school, you know, just to give them a hug and look at them for for hope. I mean they're the ones that kept me fighting and wanting to live."

"There were many days that I really didn't want to live anymore. But when you look at your children it's not a choice anymore, right? You have to. You have to get through. You have to keep fighting and searching to get well."