Image copyright Hailey Dickson Image caption Hailey was diagnosed aged 17 after her symptoms forced her to leave school

Over the space of a couple of months during her final year of high school, Hailey Dickson's world turned upside down.

Then living in Arizona, the teenager went from top of her class to having to drop out altogether.

For a girl who had grown up with travel magazines plastered over her bedroom walls with ambitions of eventually becoming a doctor, the deterioration was devastating.

"I lost all semblance of what made me 'me'," Hailey says. "I went from being strong and independent to totally dependent on my parents for daily tasks - my mom quit her job to help me full time."

It had started like a normal virus back in the Autumn of 2013, but the symptoms didn't go away.

"I was throwing up every day for a few weeks," Hailey says. "Then the neurological symptoms started."

'Constant' tremors

Every few minutes, Hailey began to experience what felt like an intense shiver down her spine. Within a week or two, it happened every few seconds.

"Soon after I began to tremor constantly - mostly in the head and neck, like I was shaking saying 'no' all the time," Hailey says.

Image copyright Hailey Dickson Image caption Hailey wearing an EEG machine which tested for seizures

She recalls a day when she tried to go to school, fighting against the tremors to sit still at her school desk.

"I felt like I could feel everyone staring at me because I had these uncontrollable movements and I just ran out there and cried," she recalls.

"There were the physical elements, but there was also the mental element of being a teenage girl and just not wanting anyone to see me like that."

The emotional toll left her feeling isolated from her peers and friends - and the physical effects kept getting worse.

"I started to have spasms in my diaphragm that would make me gasp and have the hiccups constantly... By March, I began to stutter as I had lost control of the muscles for speech," Hailey says.

The spasms left her disorientated and caused intense muscle pain in her head and neck.

Paediatricians who specialise in movement disorders are hard to come by, and the doctors she visited couldn't work out what was going on.

Some, she says, even started to suggest her symptoms may have been psychosomatic.

"Being a teenage girl, a few doctors were quick to write me off as potentially psychiatric or even attention seeking," she recalls.

Image copyright Hailey Dickson Image caption Her symptoms started shortly after she visited Nepal on a programme for aspiring doctors

As a last resort, her mum decided to take her 1,600 (2,500km) miles across the country to the specialist Mayo Clinic in Minnesota.

The first test they did, measuring electrical impulses in her body, established straight away that the movements were involuntary. Then a contrast MRI screening eventually showed their cause.

Finding a diagnosis

Hailey had a Chiari malformation - an anatomical condition where her skull shape forces the lower part of the cerebellum (the part of the brain that controls balance) to extend down into the space where the spinal cord passes through.

The condition comes in several forms. The one that Hailey had only develops in adolescence when the skull and brain are still growing. Type II and III are congenital, or present at birth.

Image copyright @_hailelujah Image caption Hailey describes her time without diagnosis as "the lowest phase" of her life

Dorothy Pope, director of the Chiari and Syringomyelia Foundation, says about three million people in the US are thought to have the condition.

Symptoms, severity and treatments vary in each case - some people may find it debilitating, while others may not realise they have it all.

"More and more cases are being diagnosed because MRI is more accessible today," she told the BBC.

Straight away, a neurologist prescribed her a fairly common medicine to help the symptoms.

The improvement was gradual, but within two months her tremors had resolved so that they were no longer visible.

Image copyright Alamy Image caption Scientists now believe Chiari is more common than the 1 in 1,000 people previously estimated

What is a Chiari malformation?

It occurs when part of your skull is abnormally small or misshapen, pressing on your brain and forcing it downward

Type I and Type II are the most common

Symptoms differ but in Type I include painful headaches, movement problems, neck pain, dizziness and muscle weakness

Considered uncommon but diagnosis improving with image technology

In more serious cases, decompression surgery may be recommended

Source: The Mayo Clinic

"It was sadly comical that such a complex situation, so difficult to diagnose, could be treated by something so simple all along," she says.

'Written off' hopes

As the symptoms eased, Hailey threw herself back into education and enrolled in the University of Arizona, but the transition was tough. On top of the time in school she had missed, she felt isolated socially from her peers.

"It was so difficult to transition from being 'sick' person to a normal girl again," Hailey says.

"While all my friends had spent the last year applying to colleges and planning their futures, I had written off all hopes for my dreams and wasn't prepared for anything."

Image copyright Hailey Dickson Image caption Hailey says her family, despite their concern, have been supportive of her ambitions

She found the first semester back in education isolating and struggled to keep up with her plans to study medicine. Feeling restless with her new-found freedom, she decided to apply for a "long-shot" scholarship to go to India and study Hindi.

Despite the odds, Hailey got a place. Her family felt apprehensive about the ambitious travel plan, but ultimately supportive of her decision.

"Everyone thought I was crazy to travel abroad after everything that happened but I wanted to be true to myself and not let my condition change who I had always been," she says.

That first trip became a catalyst for her love of the country. She switched major to global health and continued learning the language - returning for a year abroad in 2016.

Then after graduation she got a Fulbright scholarship to move to Mumbai for her research. Age 22, she lives in India and works for an organisation, Yuvaa, who spotlight youth mental health.

Image copyright Hailey Dickson Image caption Hailey filming for Yuuva (right) at one of the group's storytelling sessions in Delhi

The group, who have UN sponsorship. are travelling around the country running workshops and Hailey is filming a documentary about their work.

It's a far cry from where she was a couple of years ago, when she couldn't even hold a camera.

"I didn't become a doctor," Hailey says. "But I became a person who listens to young people, especially young girls, and takes them seriously.

"Through the documentary I want to raise their voices and concerns to a platform from which people, maybe even doctors and policy makers, can learn about their struggles and recognise them."