Sherlock awoke suddenly to the sound of his phone ringing. He looked at his clock, it read 06:42. He reached for his phone, it was Lestrade. He knew he should answer it, even if he did have a throbbing headache.
"Yes hello? What is it this time?"

Primrose Hill. Decapitation. Don't know where the bodies are though

"Right, okay, we'll be there right away"

Scrambling out of bed, Sherlock stood up too fast, suddenly feeling as though the whole world was spinning around him. "Control" he thought. Once he was able to walk, he shuffled into John's room and woke him up.
"What… what is it Sherlock" came John's muffled voice from underneath his pillow.

"Case John, it's a case"

"Uh, okay. I'll get ready and get some toast for the cab. Want any?"

"Huh? Oh, no thanks, I'll be fine" Sherlock said, knowing that he'll probably regret it later.

John rushed out the door, Sherlock barely making it down the stairs without clutching onto the rail. Sherlock's struggle went unnoticed to John, which made him happy as he didn't want to worry his friend. Climbing into the cab, a coughing fit struck Sherlock.

"Are you alright Sherlock?" John said, worried.

"Yeah," Sherlock managed to say between coughs "I'll be fine"

The fit ended and Sherlock slumped back into the seat of the cab, relaxed. Staring out of the window, he cued the driver to hurry up, even if it was only 07:13 am. Within 5 minutes they were at Primrose Hill. Lestrade was there to greet them, whilst Donovan and Anderson's team were stood around the scene.

"Young lad, 15, found it this morning. He was jogging apparently. Do teenagers actually do that? I thought they just sat around playing videogames"

Nothing but a painful grunt came from Sherlock. Suddenly he was cold and shaking, short of breath, though still hoping that nobody would notice. He couldn't let slip the pain he was in, especially in front of Anderson and Donovan, more importantly, John.

They had only spent 10 minutes on the scene before Sherlock felt his headache coming back and slowly became unable to walk. Falling to one knee, clutching his chest, the pain running through Sherlock became unbearable.

"John," Sherlock wheezed with the breath he had left "John, help me" He managed to say, reaching out for his hand before being carefully sat up.

John was sure that Sherlock was having an asthma attack, even though Sherlock has never told him whether or not he has asthma. Sitting Sherlock in his lap and propping him up against his chest, John spoke soothingly to him.

"Sherlock, I need you to calm down for me. Can you do that?"

Sherlock sheepishly nodded. Lestrade slowly moved towards the pair, but John looked at him as if to say otherwise.

"Okay, Sherlock, I need to ask you something and I need you to respond best you can understand?"

Sherlock nodded.

"Sherlock, are you an asthmatic? I really need you to answer that" John said.

Sherlock shook his head, although he was unsure himself.

John called over Lestrade to hold Sherlock up whilst he looked through his bag desperately. Finally he found it. A brown bag that he was certain he could use to calm down Sherlock. He walked back over to where Lestrade and Sherlock were and propped Sherlock up against his chest again.

"Sherlock, I need you to breathe into this" John said as he placed the bag over Sherlock's mouth. He watched as the bag was barely moving. "Okay Sherlock, please, take deep breaths in through your mouth and then slowly breathe out. Please do this for me"

Sherlock nodded, and the bag deflated until it crinkled, and then inflated again. He did this several times before taking the bag away from John and from his mouth. Putting the bag on the floor and then holding John's hand, Sherlock struggled to speak.

"John" Sherlock said, tightening his grip, still breathless "John help me… please"

"Sherlock? What's wrong?" John was confused, before noticing Sherlock's head tilted and his body slumped to one side.

"Lestrade. Come here, please, help me with Sherlock" John was clearly worried and fighting back the tears in his eyes. He had no idea what was wrong with his friend, but he knew it had to be serious.