In Sweden as part of the Global Series showdown with the Ottawa Senators, Kerfoot - who's blogging about his experience for NHL.com - planned to spend Wednesday walking around Gamla Stan, the city's Old Town district.
A series of unfortunate events got in the way.
First, his iPhone would not charge, so he went to an Apple store to get it looked at. While waiting for an assessment, he ventured off to a nearby coffee shop, where things really took a turn for the worse.
He ordered a sandwich, which he attempted to confirm did not contain any traces of nuts, to which he is severely allergic. Upon taking a bite, he realized something was amiss, and the manager informed him there were indeed cashew nuts in a pesto sauce in the sandwich.
Kerfoot explained what happened next:
Fortunately, his English was pretty good and he was very helpful in tracking me down a cab and rushing me to the nearest medical facility. In a matter of minutes, I was at the hospital, having an allergic reaction to cashews, unable to speak the native language and without a phone.
Luckily, the doctors and nurses took great care of me and I was fortunate that I had dealt with similar reactions in the past and knew what the progression felt like. I was confident that this one was not going to be super severe.
He was eventually released from hospital with a clean bill of health, but was unable to contact anyone from the team in the meantime because he was without his phone.
He was later informed the phone's battery was damaged, and was forced to purchase a brand new one on the spot.
Quite a day for the 23-year-old, who'll take to the ice with the Avalanche on Friday for the first game of the series against the Senators.