Translated from description at source:

Somebody knocked at the door. Sunset Shimmer opened it at Celestia's request. she had been living with her and Luna for two weeks since the Battle of the Bands, ever since they found her living in the sports supplies room. she had been living here for about three years until Celestia found her. the principal decided to take her to her house. after all, she cared about her, and she felt a little guilty, a 14-year old girl living alone for three years without her and her sister finding out…

When Sunset opened the door, somebody advanced at her.

"Oh my God…Adagio?", says the red-haired girl.

A haggard Adagio is caught by Sunset before falling.

"Sorry… forgive us, Sunset", sobs Adagio, "forgive us… we are sorry… and sick… my friends and me… Aria and me, we shall die soon…"

Sunset saw the girls in front of her, Aria looking as emaciated as Adagio, being carried by Sonata, who was looking pale, but healthier.

"We wanted to take revenge upon you and your friends… but we contracted a human illness… we…." , Adagio's face twists in pain.

Celestia and Luna run, taking her into the house, and leaving her in the armchair, before calling a doctor.

"Wait, what do you mean by ill? which illness?", asks Sunset.

"No, i don't know… we started to feel stomach pains yesterday… we got weaker… and we won't stop bleeding… rivers of blood… Aria and me are doomed, but please, save Sonata… the symptoms are only starting with her… save her…", Adagio says, before fainting, to the horror of Sonata and Aria.

"Blood?", Sunset asks.

Celestia hangs up the phone, scaring Aria.

"No… you won't help us… how cruel are you?", asks Aria.

"Calm down, Aria. i feel that what you have doesn't require a doctor… it's just… adolescence", says Celestia with a smirk.