Stepping on the broken tracks of my lost train of thought
Sherlock's mind was a haze, heavy smoke hanging in thick curtains, blocking out the voluminous light of reason. His conscious was dazed, slipping slightly, falling and skidding on the icy hot surface of his head. He was going to die. That had to be it. His brain was failing, falling, dying.
"Just what I thought. You, my dear Sherlock, have a fever. Don't move, don't speak, don't think, got it? I'm going to ask Mrs. Hudson for some milk."
John mumbled, his uttered breaths carrying words like ill-fated butterflies, landing on Sherlock's ears with muffled silence. His mouth cracked, the dry skin aching like the desert before rain. Don't move, don't speak, don't think. How hard could it be?
His mind wandered, down over un-trodden paths, following little cross butterflies, watching them worry. How dull being ill was.
To those with a busy mind, being sick is a blessed relief.