John had just began typing as he heard Sherlock's key hastily thrust into the lock on the door. He heard Sherlock groan as he jiggled the lock. John rolled his eyes and wondered what it was going to be this time; it was always something with the consulting detective. Sherlock had undoubtedly brought home a new body part to experiment with and as soon as he got into the flat he would begin trampling around like an elephant, clanging large pots and pans together and just generally making a ruckus. John sighed and prepared himself for the onslaught as Sherlock practically threw himself into the room.
"What's new She-" John began, pausing when he saw the state of the man before him.
Sherlock had staggered into the middle of the room where he was just barely holding himself up. He swayed slightly from side to side as his face turned new shades of pale green with each passing second. A sheen of sweat stood out on his forehead and his damp hair was plastered to the top and side of his head, lacking its usual bouncy curl.
"Sherlock?" John asked hesitantly. He had never seen him like this before.
"John. I- I-" Sherlock's swaying became more pronounced as he struggled to keep his balance. He swallowed hard and took a breath. "I don't feel well John. I think I'm going to be-" Sherlock's eyes widened as his cheeks filled with the contents of his last meal. He threw his hands over his mouth in an attempt to stop the deluge of vomit that was about to begin, but he was too late, as his body began making a "Hu-uh hu-uh hu-uh" sound and shortly thereafter a torrent of vomit began pouring out of his mouth and down the front of his body before cascading down onto the rug. His hand being over his mouth made it spray between his fingers, so he quickly removed his already puke covered fingers from his face. His liquefied brown vomit coated the front of his favorite purple shirt and part of his jacket. His shoes were almost unrecognizable under the layer of vomit now sitting upon them.
"Sherlock!" John exclaimed, rising from his chair.
Sherlock took a deep breath and managed to choke out a weak "John…" before lurching forward and heaving again, this time with a pronounced "Bleerghhh". Luckily for his shirt he had bent forward and the vomit was missing him completely and joining the already sizable puddle that had begun to form on the rug.
"Oh, Sherlock." John mumbled while joining the detective, who's hands were now braced against his knees as he continued to spill his last few meals upon the rug. "Oh, babe." John whispered while silently combing over this list of things that could have caused this in his mind. "It's okay. It'll all be okay." John rubbed the poor man's back as he continued with his "Blerrggghh hurk- hurk- hurk BLEEERRRGHH" sounds. "Just let it out honey. I'm here. I've got you. Just let it out." John repeated like a mantra, unsure if it was actually doing Sherlock any good.
Sherlock's violent retching ceased for a moment and he rubbed his hand over his stomach. "Oh god." Sherlock moaned, the pain in his voice obvious. He tried to straighten himself up but as he did, the smell radiating off of him and the floor hit him and his stomach flipped again, forcing him to unleash another wave of vomit onto the carpet. John smoothed Sherlock's moist hair off of his forehead and replaced it with the back of his hand. Just as he had suspected, Sherlock had a temperature. With every new surge of vomit Sherlock's bent back arched and all of his muscles strained. He could feel his own blood vessels beginning to burst. The sour taste of bile stayed on his tongue between his episodes of puking. Sherlock coughed and spit, the flood of vomit coming to another momentary halt. He looked at John with a look the doctor couldn't place, he had never seen Sherlock with that look before. John took advantage of Sherlock's momentary ceasefire to hurry to the other side of the room and pick up the bin Sherlock kept near his chair, in an attempt to spare the already soiled rug any more stomach contents being spilled upon it. As John moved he heard Sherlock whimper again. "Let me just grab-" He began but the detective cut him off with a low, whimpered apology.
"I'm sorry." Sherlock mumbled. John froze and turned toward the detective, confused, but before he had a chance to respond Sherlock's eyes fluttered shut as he collapsed into the puddle of his own vomit.