Harrison Hayes was studying for his A-level exams when he was struck down with a mysterious illness.

The teenager noticed that he became short of breath easily and had to stop for regular breaks whenever he took a walk.

Over the weeks, the odd symptoms persisted, progressing to general fatigue and random body aches all over her body.

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Harrison, who likes to be known as Harry, visited doctors but doctors were unable to determine what was causing his declining health.

After several trips to A&E, Harry says he was misdiagnosed on several occasions, said he had everything from a collapsed lung to bad acid reflux. He was eventually prescribed steroid tablets which appeared to improve his condition, seeing him return to his favorite sports including football and cricket.

But, several weeks later, while attending parents’ night with his mother, Harry became so tired that he couldn’t sit up in his chair and had to lie down.

His family were so worried that they took him to his GP several times and eventually blood tests were taken.

A few days later, Harry’s condition began to deteriorate rapidly. The 22-year-old became bedridden to the point of being unable to dress himself.

“My mum had to help me change,” he told the Manchester Evening News. “She brought me all my meals. I couldn’t get out of bed.

It was late at night in mid-December 2017 when Harry’s family were rushed to hospital. Less than two months after his symptoms started, Harry’s test results were back – he had Addison’s disease.

Addison’s disease, also known as primary adrenal insufficiency or hypoadrenalism, is a rare disorder of the adrenal glands located at the top of the kidneys.

The adrenal gland is damaged in Addison’s disease, so it does not produce enough cortisol or aldosterone. Around 9,000 people in the UK have Addison’s disease, with over 300 new cases diagnosed each year. If left untreated, it can be fatal.

It can affect people of any age, although it is most common between the ages of 30 and 50. It is also more common in women than in men.

Early-stage symptoms of Addison’s disease are similar to other more common health conditions, such as clinical depression or the flu.

Harry was immediately rushed to intensive care and thankfully recovered. He will now have to take medication to relieve his fatigue for the rest of his life.

“I was so weak,” said Harry. “The doctor saw the blood tests and said it was a rare disease, but she thought I might have it.

“In mid-December I got a late night call telling me to go to the ER. They hooked me up to all kinds of stuff and put me in intensive care.

“If I don’t have my meds, I’ll start to feel tired. It can be fatal. When I was in the hospital they told me that if it had been another week I could have died.

“I didn’t realize how scary it was back then. This made me very delirious; I didn’t know what was going on. I had a hard time understanding the situation I was in.

“When I got home I realized it was a very scary time and I still talk about it with my family now.”

Harry is now set to run the Manchester Marathon on April 16, raising money for the Addison’s Disease Self-Help Group (ADSHG).

The biggest problem with Addison’s disease is often the diagnosis, as the symptoms can often be mistakenly associated with other medical conditions,” said Harry, who lives in Leeds.

“This means that diagnosis is often a long and horrific process, and can sometimes lead to death if the disease is not diagnosed in time. This is my main motivation for raising funds for this cause, to raise awareness for a very rare disease, which will hopefully lead to fewer people going undiagnosed in time.

“I wouldn’t be here if not for the amazing doctors and nurses who diagnosed and treated me.”

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