The thing about psychosomatic pain is that it hurts.

Which is why, two days into Sherlock's fit of bright blue sulks, John finds himself unable to manage the stairs down from his bedroom without the cane he'd hoped never to need again. Why he drinks his breakfast, except for the little white pill which he knows is only sugar and vitamin A, but which he hopes his misbehaving brain will think is something stronger. Why he slumps into the battered chair in the sitting room and stares at things which only he can see.

Why Sherlock reaches for his violin.