"He was very sick. He looked at you like he was just giving up ... it was horrible."
He lost almost a kilogram, Conning said, and was so malnourished he couldn't hold his head up.
Posting her journey on social media, the mother-of-two said she watched her son "get worse by the day" as he went from a size three nappy to a size one.
Arthur underwent surgery for laryngomalacia, which he has been diagnosed with. It's a common condition in infants, when the tissue just above the vocal cords is especially soft and breathing is noisy.
But after two weeks of "no answers" Arthur was transferred to Auckland's Starship hospital where he has gained 200g and is currently tolerating 25ml of milk an hour through a feeding tube.
A child his age should have 50 to 60ml an hour, Conning said.
He needs to be healthy enough for more testing next week, and for results back on others.
"Now he seems a lot better and he's actually talking to us at the moment," Conning said.
"I just want answers. I just want to get the right care that he needs. It's not fair. I've not been home in almost a month now."
Her partner and daughter are back home in Te Aroha while Conning is in Auckland, with the help of her mother.
Conning's friend Lee-Anne Murray has set up a Givealittle page to help cover the cost of travel and the "extra expenses" for the Connings. The page has garnered almost $4000 in two days.
Conning was shocked and surprised by Murray's gesture, and overwhelmed by the support. Conning has previously helped Murray fundraise for breast cancer.
"It's amazing. I thought maybe a couple of hundred [dollars] but not that, it's absolutely overwhelming," she said.
"It's amazing, I don't have to think day-by-day."
Any money not used by the Connings will be donated to Starship hospital.