13-year old Karanbir Cheema, who went by Karan, died in July of last year, with his school saying he was chased by a student who threw cheese down his shirt.
A boy of the same age - who no longer attends the school - was arrested under the suspicion of attempted murder, but charges were not pressed.
Paramedic Kierin Oppatt says the school underestimated the severity of Karan's reaction when reporting it to 999.
The boy was covered in hives and 'gasping for air' when responders arrived to the scene of exposure - West London's William Perkin Church of England High School.
Opatt said: "I went to the vehicle and called the communications centre and informed them that our patient was in cardiac and respiratory arrest.
"And that I required the assistance of an advanced paramedic and additional crews at the job."
By the time reinforcements had arrived, Karan was unconscious and had stopped breathing - the result of anaphylactic shock.
He was then rushed to Great Ormond Street Hospital, where he died after a 10-day stay.
His parents, who were there when Karan died, say they're still seeking an explanation for their son's death.
'We want answers'
Karan's mother Rina Cheema said: "We want answers. I am devastated as a mother after losing my son and my family have lost their brother. He was a very, very bright young boy.
"He was so bright he could have been anything he wanted."
Death by dairy
Dairy allergies are not entirely uncommon, and have been the cause of death of a number of young people over recent years.