Brianna!
She wanted to throw up because she was throwing up.

Eliza walked as quickly as she could through the corridors of St. Mungo's, attempting to look busy or in a hurry. Which she technically was. She and Brianna only had a short amount of time with the free examination room, and Eliza wasn't sure if she could trust anyone else in the hospital to not tell Dedalus (or the healers she'd been seeing since the attack) that she was getting ill. Brianna would definitely be able to figure out what was wrong, and if she couldn't then she would approach other people. There was no reason to get anyone upset or worried when it was just a bug, or a poor reaction to something.

A lurch in her stomach made her skid to a halt, and Eliza looked frantically around the empty corridor for a place to get sick. Oh bother.

After a few nauseating minutes in a broom closet, Eliza disposed of the bag she'd managed to latch onto, and pulled herself into the examination room, ready to topple over from the sickness and the exertion of nearly sprinting across the hospital.

"We need to figure this out," she groaned, slumping into a chair beside the examination table; she definitely did not feel like she could push herself up on it.