When Abi Burton returned to England after missing out on a medal at the Tokyo Olympics, she felt "really, really lost".

But Burton, 22, had no idea just how tough life was about to get.

One year on from losing to Fiji, she was wrongly sectioned for 26 days, spent 25 days in an induced coma, and contracted pneumonia twice.

This is her story.

'I couldn't function properly in daily life'

As Burton looked back on her first Olympic experience, she knew she and her team-mates will have inspired a new generation of sevens players. It was not enough.

"You feel empty because you work towards an Olympics for so long and then you don't come away with what you want to achieve," she tells BBC Sport's Jo Currie.

Rugby had defined Burton's life, but she was soon given a "new perspective".

Burton, who made her England debut aged 18, says she first noticed a change in her behaviour when she started to feel "really down" and had no energy.

She remembers being put on anti-depressants because "the first thing people go to is mental health".

"I was in training camp and I hadn't been selected for the European tournament, which was to help us qualify for the World Cup," she says. "It was the first tournament I hadn't gone to in my four years of playing.

"They said to have a bit of time at home, to try and figure out what's wrong."

Then - on 15 June 2022 - she suffered her first fitting seizure, while sitting at the dinner table with her mum.

After being assessed in hospital she was discharged as it was her first seizure and "could also be the last".

But her behaviour would change significantly.

"I went from being a timid, unresponsive person, to really quite manic behaviour," she says. "I was really aggressive towards my parents, siblings and even the dog."

Burton does not remember that period of her life - including two tournaments she played in. She even told her parents she did not want them at the London Sevens - the first time they would have been able to watch her in England in the national shirt.

"As my behaviour got a lot worse, I couldn't function properly in daily life," she says.

After more seizures, Burton was sectioned, and says doctors thought she had stress-induced psychosis.

"My mum and dad had to basically just let them take me and hope they could fix me," she says. "I can't imagine how scary that was for them."

'I rugby tackled a few of the security guards'

Burton spent 26 days in Fieldhead - a psychiatric hospital in Wakefield - and her behaviour continued to deteriorate.

"I was being treated for psychosis, basically," she says. "They didn't rule out an autoimmune illness, but they didn't test me for it either."

Burton's behaviour and seizures did not improve until her father was approached by a member of the autoimmune diseases research staff who had reviewed her notes.

"He came up to my dad and said: 'I think your daughter has something physical, I don't think it's mental."

After tests, Burton was diagnosed with autoimmune encephalitis, which occurs when the body's immune system mistakenly attacks the brain.

Richard Robinson - chief medical officer at the Mid Yorkshire Hospitals NHS Trust - describes it is a "very rare" disease which presents a "major challenge for clinicians worldwide to diagnose and investigate".

After Burton's diagnosis she was moved to a different hospital but was initially treated in the acute assessment ward as there were no beds available in the stroke and neurology unit.

"It was a battle for my dad every day because he was trying to stop me from being aggressive towards people, but he's no doctor so he didn't know how to treat me," she says.

"I was so poorly. I knocked a few people out of the way trying to escape the ward. I rugby tackled a few of the security guards apparently, trying to bust my way through the doors, which are magnetic and don't open normally."

Once a bed became free on the stroke and neurology unit, Burton's family made the difficult decision to have her put in a coma so she could receive plasma exchanges.

"They knew they couldn't treat me," she says. "I was too agitated, it had gone too far."

Burton spent more than three weeks in a coma - at the same time her team-mates were competing in the Commonwealth Games in Birmingham.

'This isn't me'

Burton contracted pneumonia twice while she was in the coma and when she came out of it she was unable to walk and talk, and had lost more than three stone.

"I don't think I realised how poorly I was when I first woke up, and I had no desire to ask," she says.

"I had no muscle. I thought: 'This is awful. This isn't me. I don't look like me.' It was really tough."

The physical challenges were obvious, but Burton also had to contend with the fact she had missed out on a home Commonwealth Games.

"I grieve for that part because it was taken away from me," she says. "For so many years, rugby was my identity and then I couldn't play."

But Burton was not going to give up. After completing an intensive programme set by Team GB's doctor, she returned to training with her team-mates last month.

"I'm very stubborn and I like to do things a certain way," she adds. "When I was told I couldn't, I said: 'I am!'"

What's next?

After a whirlwind 2022, Burton has set herself targets both on and off the rugby field.

On it, she wants to return to the World Sevens Series this year, then make amends for the disappointment of Tokyo, at the 2024 Paris Olympics.

"Next season, a medal at the Olympics is the goal and I want it to be a gold," she says.

She also wants to raise awareness of autoimmune encephalitis in the hope no-one else has to go through what she has.

"If I could never play rugby again then I would be gutted, but if I can raise awareness to help change the protocols in the NHS, then I'd be content with that," she says.

"I could never have been diagnosed, and I could have died if I hadn't. It's hard to imagine what the outcome could have been. It could have been a lot different."