The Doctor didn't really know what to think when she first felt it, a strange sort of mild prickling in her face, specifically her nose, so she ignored it and wondered if it would go away in a minute. It wasn't exactly bothersome, and she wanted to fix the water slides so that Yaz could finally have a go. She'd already done the outside work on a separate occasion - one where she was interrupted and promptly forgot about it - so all that was left was the inside.
The room where she assumed the last issue was could only be accessed by crawling through the vents. Well, no, that was a lie. There was the long way round, but she didn't particularly fancy walking eleven miles (no exaggeration) just to reach a place she could reach via the vents in five minutes. She also doubted Yaz - who had decided she didn't want to wait in the swimming pool room by herself due to its vast eeriness - would want to walk either.
So there they were, crawling through the vents, the strange sensation in the Doctor's face only growing more prominent.
Upon realising her eyes were now watering a bit, she stopped, squinting as she tried to figure out what was going on.
"Doctor?" Yaz stopped. "What is it?"
"Not sure yet." She manoeuvred to sit against the wall, blinking one eye and then the other before scrunching her nose up. "Give me a sec."
Yaz looked mildly concerned. "Is something wrong with the TARDIS?"
"No, no, nothing like that..." She hesitated again as she focused on the prickling that was now becoming sort of an itch.
"Ok, well, my back's killing me, so can we maybe-"
The Doctor help up her index finger at her, signalling to wait a second.
Yaz sighed and gave up, moving to sit beside her and waiting.
"Yaz..." she said slowly.
"Yeah?"
"Don't mean to alarm you, but something might be wrong with me."
"Wrong with... what is it?"
The Doctor rubbed her face. "There's a funny feeling in my face. Or, nose to be exact."
"Ok... what sort of feeling?"
"Like..." she sniffed, which made it worse, causing her to frown. "Like..."
The Doctor tapped her fingernails on the vent wall, poking it.
"Like that. Except more prickly."
"More-"
"Ah!" She exclaimed, wriggling her nose again. "It's getting worse. Or... better, I'm not sure."
Yaz was beginning to look alarmed now. "Worse how? What do I do?"
"I don't know! I..." her eyebrows furrowed, her breath hitched once. She just had time to look scared for a second before the itch overwhelmed her and she snapped forward, her forehead hitting her knees.
"KHTISHOO!"
Yaz jumped, before relief flooded her face and she started laughing.
"Oh..." The Doctor grinned as she relaxed. "Feels different with a new nose, s-suh... hihtCHOO! TSCHOO! Sorry for scaring you."
Yaz giggled. "It's fine, Doctor. You done?"
She shook her head. "D-don't think s-sCHOO! H-hh..."
Her chest heaved with each shuddering breath she took.
"HASCHOO! HAH-KTISCHOO! Hh-HIPTSCHOO!"
Yaz began to get concerned again now, especially when she noticed that the burst of movement from each sneeze was stirring dust from every surface of the vent.
"Doctor, you have to stop. You're making it worse."
"C-ca-hh... c-can't... d-don't kno-h... h-h-ho-PTSCHOO!! AHISCHOO!!"
Yaz fished in her pockets for a tissue and pressed it hard against the Doctor's nose. She could feel it twitching feverently and held her breath, but the tissue seemed to help and she managed to get it under control for the time being.
"Th-thanks Yaz," she breathed.
"Don't talk, just focus. You're stirring up more dust when you sneeze."
She nodded slowly, and all was still for a few seconds, before she grabbed the tissue from Yaz and ducked to the side. "HYISCHOOO!"
She pinched her nose hard after that, muttering a shaky, "Sorry, couldn't stop it."
Yaz looked at her and the Doctor shook her head, answering before she had to ask. "No, s-still have to... hh... s-sneeze-hah...YIESCHOO!"
With nothing else working, she balled up the tissue and pressed her fist against her quivering nose. It helped for a little while, but only stared off the inevitable.
"Ptschnx! Kih-tchx!"
The stifling at least prevented the disturbance of more dust, but it didn't help get the dust that was already in it out of her nose, and god she could feel it itching at her. Her lips were permanently slightly parted, her eyelids fluttering.
The concern was returning to Yaz's expression now. This definitely wasn't normal, right? She must be really allergic to it.
"Did you know you're allergic to it?"
She shook her head slightly, trying not to move too much. "New body, n-new... h-hih... new rules...hah... ngtsx!"
As she wound up for another sneeze, Yaz sighed. "Right." She pulled the Doctor's fist away from her face.
"Y-Yaz what-h-hUH... w-what are you d-hih-doing? I still h-have to HAH-"
The moment her eyes slammed shut, she felt Yaz's finger under her nose, and the tickle faded in an instant.
The Doctor frowned. Hesitantly, she opened one eye, and then the other.
Yaz winced, but her expression looked confident.
"Better?"
"Y-yeah, actually."
"Right then. Shuffle along, we can get out like this."
So she did, sidling along the vent wall with Yaz keeping her finger steady under the Doctor's nose, until they could slip out of the end of the vent and the Doctor allowed herself to give in to her nose.