Ayris said she wasn't even sure how the break occurred and had purposely downplayed her pain leading up the event.
"It's been a little niggly for a while - when I got off a plane in America [before last month's world championships in Oregon] for a session I felt it a bit but I just thought that it was from the travel.
"I kept training on it, it kind of went away, and then it came back a bit. We were strapping it up for training sessions, didn't modify any training, and then after competition we got it scanned to figure out what was really going on and it was fractured.
"I had probably downplayed it in the past two weeks building up to this but I didn't want to make it a thing if it wasn't a thing."
The break has forced the rising star to cancel a planned athletics campaign in Europe and instead return to New Zealand to rehabilitate the injury.
"I'm going to go home, put my feet up and let this bone heal," she said