How much would you pay for one more day, one more month with someone you love?

WASHINGTON — If someone you love is dying, how much are you willing to pay for just one more day with them?

Doing the math, Melany Knott figured it cost about $1,100 a day. That got them 21 months.

"No regrets," Knott said. "I wouldn't change a thing. And I won't wonder about anything."

The Knott family auctioned off chain saws, goats and guns to raise some of the $695,000 they spent. They raided their savings, college funds, maxed credit cards and doubled down on the double shifts. They did fundraisers at the county fair and ran online tote bag sales to pay for untested treatment offered at a medical clinic in Mexico.

This was not the battle for a cure to their 13-year-old daughter's monstrous, fatal brain cancer.

The doctors behind the mystery treatment have published zero studies on their findings and won't even disclose the ingredients of the custom, chemotherapy cocktails.

But the Knotts were willing to gamble. One more day. One more month with their child. Maybe, one more year, even?

This began 21 months ago, when the youngest of their four daughters, Kaisy, was having severe headaches. She was diagnosed with diffuse intrinsic pontine gliomas (DIPG), an aggressive, inoperable, incurable, 100 percent lethal brain cancer.

"It felt like I was being stabbed in the head," Kaisy explained to me at the airport last summer, on her way to one of her $33,000 treatments in Monterrey, Mexico. And then, the pain stopped.

For a while, Kaisy was hailed as the Miracle of Monterrey.

She went from being unable to raise her right arm or walk to swimming in the ocean, kayaking, riding roller coasters and showing her hog and steer at 4-H competitions.

Other families started flying to the Mexico clinic from around the world – Norway, London, Italy, Australia – to take in the experimental and controversial cocktail of drugs that doctors injected into the children's arteries.

"There she is! It's Kaisy!" they would say when they saw her in the halls of the Mexico clinic, Melany said. And medical technicians had to act like bodyguards to shield Kaisy from the crowds.

Her Facebook page, Kick Butt KK, attracted thousands of followers. All this lasted 21 months.

Kaisy died on Monday.

"Mom, I can't do this anymore," she told Knott, in their Mount Airy home Sunday night. She went from showing animals at a fair last month to being bedridden in a matter of weeks. On Monday, there was one, last "Mom." And then she was gone.

Would Knott do anything differently?

All that flying, the fundraisers, nearly $700,000 gone. She has three other daughters, all in their teens, one in college.

Nope.

The U.S. doctors told her to "go home and make memories," she said. But Kaisy – the little girl who always won big awards showing her giant livestock – is a fighter. And Knott was going to fight for every single day.

"You do anything for your kid," she said.

They decided, in these fighting days, they would do anything Kaisy asked. They were lucky that Kaisy had simple, country tastes. No Make-A-Wish stuff. No trips to Disney World or Paris.

They dropped everything to go to Ocean City on a Thursday when they didn't have hotel reservations. They swam, paddle boarded, got Starbucks whenever she asked, made 52 paracord bracelets when she became obsessed with making them.

"We were looking for quality," she said. "And the Mexican treatments were less invasive and gave her quality."

She thinks that American doctors gave up too fast, giving her eight months to live after the first diagnosis. And she said they were timid about treating her after the Mexican infusions, refusing to buck decades of traditional radiation therapy.

Knott was thrilled when President Donald Trump signed the Right to Try Bill in May, which allows people with life-threatening illnesses to get access to experimental treatments and to bypass the Food and Drug Administration for approval.

She supported a recent bill to raise awareness of DIPG, and even though it makes her uncomfortable to mingle in these circles, she'll keep doing it. Because being uncomfortable is what Kaisy taught her to do.

"I love all my girls for different reasons," Knott said. "I don't love any of my other girls for the same reasons I love Kaisy."

"She was the courageous one. The one who made me come out of my box" said Knott, 40, a daughter of truckers who has lived her whole life in rural Maryland, with hogs, horses, steer and dozens of chickens.

Kaisy made her mom ride a roller coaster for the first time, go to the beach, ditch a day of work. She flew on a plane for the first time, got a passport, left the United States for the first time, rented an apartment in Mexico, became best friends with a Mexican medical school student named Caesar who took care of Kaisy when they were there for treatments.

And on Wednesday, Kaisy did it again.

It took Knott 15 minutes of stalling to go into the funeral home. She threw up twice outside.

"I said: 'You're doing it again, Kaisy. Making me do something I never thought I would do,' " Knott told me. "Then I busted out laughing.

"The funeral director looked at me like I was nuts," she said. He was already freaking out because the funeral is going to be too big for his little parlor, and he had to move the whole thing to the biggest space in their tiny town – the local fire hall.

And then Knott had to explain to the nervous director that for 13 years, Kaisy challenged her mom. And dang it, even in death, she was doing it again. Knott has a deep fear of bodies, of the cold, limp feeling of death.

But Kaisy liked her hair braided, only by mom. And Knott knew that Kaisy wanted her hair done, one last time, only by mom.

So after puking and laughing, she walked up to her child's body – clothed in the T-shirt, shorts and tie-dye Crocs she put out for what she hoped would be her first day of school this week – and braided her hair.