One day, little Louie Bell was his usual happy self enjoying his big sister's birthday, the next, the Auckland 2-year-old was writhing with stomach pain.
Within a week, biopsies and scans had led to a diagnosis of a rare and aggressive cancer called embryonal rhabdomyosarcoma, which originally forms in soft tissue.
It is eight weeks since Louie's tumour was found growing around his bladder and prostate and pushing against his spine.
Because of its location, an operation is too risky and Starship doctors are using weekly chemotherapy sessions as well as radiation therapy to attack the tumour, a regime that may run for a year.
Though doctors have estimated a 70 per cent chance of cure, it is a type of cancer that can return and treatment with radiation comes with a risk of incontinence, infertility and impotence.
Louie's parents, Maxine and Matt Bell, are hoping to take their son to the United States for a treatment only available there which can reduce the risks.
Called proton radiation therapy, it uses high-energy beams which can be finely targeted, thereby reducing collateral damage.
It has been available in the US since 1990 but its use has not spread widely because of its high cost, according to a report this year in Medical News Today.
Starship doctors have been brilliant, says Maxine, and have sent Louie's scans to a doctor in the US who specialises in proton radiation therapy to see whether it would help the infant.
"Proton therapy works best on areas that are not too big," says Maxine. "He has got quite a large tumour but luckily it hasn't spread anywhere else. We are just waiting to see whether he thinks it's a go. Fingers crossed."
A GiveALittle appeal has been launched to help the family with medical costs and proton therapy should he qualify to receive the treatment in America.
Louie, she says, is like any 2-year-old. "Most days you wouldn't know he is going through chemo apart from that he's lost his hair and he's got a [urinary] catheter."
The suddenness with which their lives changed still stuns. The first sting was when Louie couldn't pass urine. "His bladder was at capacity and was backfilling into his kidneys, causing him quite a lot of pain."
"It is devastating. In that first crazy week before we got the diagnosis, it was 'no, it can't be that, this isn't going to happen to us'.
"I have moments of being just absolutely gutted and bawling my eyes out. But we don't have a choice. We just have to get him through it and get each other through it."
Matt has a stressful job as a project manager on a huge construction site but his bosses have given him time off as needed, she says.
"Matt's sister passed in 2011 from a cancer in her brain," says Maxine, "She left behind four kids, so that is enough for one family. And then we get this. It feels extra unfair."