The cause of death for a 17-year-old rugby player who collapsed days after leaving the hospital has been revealed. During a recent inquest into the death of Lilly Day, which was held at Cheshire Coroner’s Court in England, it was revealed that the teenager died from a ruptured spleen after suffering "a rare complication" from a virus, according to local newspaper the Warrington Guardian. The U.K. court was told Day had attended an appointment at her doctor's office in Warrington, Cheshire, on Feb. 14 of this year. She died four days later, according to online records. After attending her doctor's appointment, Day was diagnosed with a viral upper respiratory tract infection, the Warrington Guardian reported. However, she didn't get any better and went to the hospital the following evening on Feb. 15 at around 8:30 p.m. local time, complaining of a cough, sore throat and nasal congestion. The hearing heard that Day — who previously played for teams including the Warrington Wolves Women’s Super League and was believed to have been being observed by both England and Ireland's national teams — also had puffy eyes and swelling in her neck, per the publication. Medics thought a change in environment might have played a factor in her illness, the publication reported, so the teen — who had been fit and healthy before starting to feel unwell since the beginning of January — was told to refer for allergy testing. She continued to feel unwell, experiencing symptoms including nausea and diarrhea, before collapsing in her bathroom at her home on Feb. 18 of this year, according to the outlet. Day remained conscious on her way to Warrington Hospital, telling medics she had symptoms including lethargy, tiredness and pins and needles. After arriving at the hospital, Day lost consciousness after having her blood taken before going into cardiac arrest. She was pronounced dead at 11:45 a.m. local time that day, per the publication. A post-mortem examination has since confirmed Day died from a ruptured spleen, which was caused by glandular fever, the Warrington Guardian reported, adding that she'd suffered "a rare complication" from the viral infection. The U.S. term for glandular fever is infectious mononucleosis (mono), which is spread through saliva, per the Mayo Clinic. Mono is often called the kissing disease and though you can get it through kissing, "you can also be exposed by sharing a glass or food utensils with someone who has mono," according to the medical center. Senior coroner for Cheshire, Jacqueline Devonish, ruled at the hearing that Day's spleen didn't rupture until the morning of her death, so there was nothing that could have previously alerted medics, per the Warrington Guardian. Day's medical cause of death was listed "as hypovolemic shock due to intra-abdominal haemorrhage, severe splenomegaly with rupture, and Epstein-Barr virus (EBV) induced infectious mononucleosis," the newspaper stated. The Warrington Girls Community Rugby League Club, which Day previously played for, was among the many paying tribute to the teen following her death. The team set up a GoFundMe to raise money for Day's family, writing in a description, "Words cannot express the depth of our sorrow. We are heartbroken for Lilly's family and offer them our deepest condolences during this incredibly difficult time. We also extend our love and support to her many friends and teammates who are struggling with this loss." The Warrington Wolves also previously posted a photo of Day's jersey on Facebook, alongside the message, "The Warrington Wolves are deeply saddened to hear of the passing of Lilly Day. Lilly made her debut for our Women’s Super League team last season, proudly earning heritage number 95." "Our thoughts are with Lilly’s family, friends, and teammates during this incredibly difficult time. 💛 #LillyDay95," they added. Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories. During the court hearing, Day's mom, Dawn Boadey, said of her daughter, “Lilly loved life. She had ... many friends. She was happy to go out. She worked hard and played hard," per the Warrington Guardian. “I don’t know a person that didn’t like Lilly," she added, according to the newspaper. The Cheshire Coroner's Office, the Warrington Girls Community Rugby League Club and the Warrington Wolves Foundation did not immediately respond when contacted by PEOPLE for comment.