It's hard to imagine the pain of childbirth unless you've experienced it first hand. But on the pain scale, the amputation of a finger or toe is worse. Just.
Then, a whole 10 points on top of that - the worst pain ever inflicted on a human being - is a disease called Complex Regional Pain Syndrome (CRPS).
It's incurable, and so bad, that the very rare neurological condition is nicknamed the "suicide disease". Melbourne philanthropist Chantelle Baxter knows why.
In January, the 32-year-old was diagnosed with the horrific disease, one that started with pain from a twisted ankle, and has seen her endure unspeakable torture 24 hours a day. She is now fighting for survival, hopeful for remission, in a specialist treatment centre in the US.
"When the condition first spread, I ended up in Emergency with full body tremors and in an incomprehensible amount of pain - my body had gone into shock," Baxter told news.com.au from her hospital bed.
"It's very difficult to describe the level of pain.
"I can't even give words to it.
"I had no idea the human body was even capable of producing that much pain.
"At my worst, my body felt like I was being dipped in boiling oil - and it was everywhere.
"My legs felt like the bones were slowly being crushed - and it was relentless, hours and hours and hours of the worst pain I'd ever experienced.
"I don't even remember making the phone calls, but apparently I called a friend in Australia and begged him to jump on a plane and come to America and kill me.
"I just kept saying 'I have to die' over and over again - there was just no way I could live with pain that high."
Baxter has spent her life helping others, co-founding one of Australia's fastest growing non-profit organisations, One Girl, helping thousands of girls and young women in Sierra Leone, West Africa.
In 2011 she was named one of Melbourne's Top 100 Most Influential People and was listed as one of the Top 30 Under 30 Entrepreneurs.
Today, she lives in pain, hopeful for an end to her misery.
"It all started after a hike in Portland, Oregon," she said.
"I'd been having a bit of pain in my ankle for a while, but I got home after a hike where I'd twisted my ankle, and my whole left foot felt like it was burning and it had started to swell.
"I was flying back to Australia literally the next day - and by the time I landed I could barely put any weight on left foot.
"By that stage my foot was a strange purple, red colour and incredibly swollen.
"I knew something was very wrong - so I spent the next six weeks getting every test under the sun - MRI, ultrasound, bone scan, CT scan, blood work - I visited specialist after specialist and none of them could give me an answer about what was going on ... and eventually I gave up trying to find an answer and flew back to the US, where a doctor finally diagnosed me with CPRS."
CPRS is believed to be caused by damage to or a malfunction of the peripheral and central nervous systems, but frustratingly, the full cause is not understood. It most often affects a person's hand, arm, foot or leg after an injury. And while most people recover, the condition can recur and in severe cases, persist for years.
Within a month of diagnosis, the CRPS had spread into Baxter's calf before rapidly spreading through her entire body.
"The level of pain I was feeling in every part of my body told me I was dying," she said.
"It felt like from head to toe I was being burnt alive - and it was a hell that existed inside my own body.
"For the first four weeks after it spread, we struggled to get the pain under control and I spent a good chunk of that month talking and planning my own suicide."
Baxter is currently undergoing a 10-week treatment programme in the US and is making progress getting her pain down to a manageable level.
"I believe that I will go into remission, I just need to keep at it," she said.
"I get three to five chiropractic adjustments a day to release the pressure on my vagus nerve, plus I get hooked up to three different types of machines to help reduce the pain and rehabilitate my nervous system.
"They all use electrical current to calm the nervous system in different ways.
"I'm also doing up to five hyperbaric oxygen chambers sessions per week.
"Every treatment is different, and I knew from the time I was diagnosed that I wanted to get well -- and ideally I'd get well without the use of any kind of hardcore drugs.
"For most people diagnosed, they can hope for nothing but pain management -- nerve blocks, ketamine and a variety of pain medications, but I didn't want that. "Many end up stuck on medications, and very powerful ones, for their entire lives, and are forced to keep upping the dose because their body just learns to tolerate it.
"For me, it's important that I actually get to the source of what cause this dysfunction and try to heal from there.
"This has, by far, been the most difficult experience of my entire life.
"I've spent so much of my life helping other people, and never thought I'd be in a position where I'd need so much help myself.
"My goals are to stop it spreading further, be able to walk a reasonable distance without pain and to sit at a table."
The next step for Baxter's treatment is in Bologna, Italy, to try a drug called Neridronate Acid, which has been used there to treat CRPS for years with an 80 per cent success rate. The Neridronate Acid will be infused into her body in four treatments across a two-week period.
"When I first left the hospital I couldn't walk without pain, and I was spending most of my days inside in bed or on a couch with my legs up," she said.
"I'm fighting so hard to get better, and I believe that I will.
"It's just going to take some time to get there."
• In an emergency: call 111
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633, or text 234 (available 24/7) or email@example.com or live chat (between 7pm and 11pm) http://livechat.youthline.co.nz/mibew/chat?locale=en&style=youthline
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Samaritans 0800 726 666
• Healthline - 0800 611 116
• For more information about support and services available to you, contact the Mental Health Foundation's free Resource and Information Service on 09 623 4812 during office hours or email firstname.lastname@example.org