"Then he puked ... and the nurse said, 'Oh, that just doesn't look right,' and went and got a second opinion.
"And thank God she did because the second opinion got us to get a blood test before we went home."
Tests confirmed Jethro's kidneys were failing. He was taken into surgery immediately and put on dialysis.
"I'd lost my father to kidney failure a few years ago ... I just thought straight back to my dad being sick with it and I thought it was going to be living that again," Miss Gantley said.
A few days later Jethro was diagnosed with Atypical Haemolytic Uraemic Syndrome (Atypical HUS).
The genetic condition affects children and causes blood clots, resulting in kidney failure and high blood pressure.
More than half of sufferers die within a year of being diagnosed.
This week was the one-year anniversary of Jethro's diagnosis, a positive milestone for Miss Gantley.
"Down the road he will require a transplant. But the blood problem is mainly in the liver - so unless he had his liver and kidneys transplanted, there's no way of curing it.
"But that's such a risky option that the doctors will only do that if he's on his death bed."
After his diagnosis, Jethro underwent an intense treatment in which his blood was removed and cleaned.
Now once a week he receives new frozen plasma - a blood product - which is keeping him stable.
Last month, the experimental drug Solaris was approved in the United States for children with Jethro's condition. A clinical trial is being conducted, but he does not meet the requirements to be part of it.
The drug slows the blood clotting process and gives sufferers a more stable life without requiring weekly infusions. But the treatment costs $500,000 a year.
Miss Gantley is determined to get her son the drug because the alternative would be unthinkable.
"I'll basically watch him die. I don't know how long it will take, the specialist doesn't know how long it will take, but it'll happen."
Pharmac does not fund the drug because of cost. Its medical director, Peter Moodie said that as well, Solaris did not have the data to support its benefits, which was often the case for treatments for extremely rare illnesses.
Auckland District Health Board chief medical officer Dr Margaret Wilsher said the board was providing full support to Jethro and his family.
Miss Gantley has set up a trust for Jethro so people can donate and is also appealing for other fundraising ideas.
She said she was only doing what she had to to keep her young son alive.
"I think any mother would do this if their child was sick enough - you just do what you can to help them."
MEDICAL MENACE
Atypical Haemolytic Uraemic Syndrome:
* A genetic disease which causes clotting in the blood.
* Affects only children.
* 60 per cent of sufferers die within a year of diagnosis.
How to donate:
The Jethro Morrow Health Trust
38 9012 0102064 00
Kiwibank