Personally, I think Sherlock was just acting ill in this scene and he was fully healed at the time. His fiddling with the morphine was probably just an act to persuade CAM that he is addicted to painkillers and thus easier to cheat. The fact that they were meeting at Speedy′s seems to confirm this: Sherlock is probably no more in the hospital, so he just came to the restaurant from upstairs, from his flat at 221B.
I find it suspicious how Sherlock is seemingly out of his wits when playing with CAM′s spectacles, yet he is lucid and very cunning and perceptive when offering „deal with the devil“ to CAM just a few minutes later. And if this scene really takes place shortly before Christmas, as it seems to (since I doubt CAM and Sherlock spoke about Mycroft′s notebook in august and Sherlock delivered it to CAM only after so many months, in december), it′s one more reason for suspicion: Sherlock was shot in early summer, there′s no way he still needs medication in winter.
Because CAM has all the blackmail information in his hands and guards it well in his Appledore „fortress“, he currently holds all the aces of this game and Sherlock needs to find some way to „break throught the walls“. He paints himself as gullible and weak so that he can be invited into the lair of his opponent. I think he knows quite well what he′s doing and he succeeds with this plan - it′s just unfortunate that CAM′s blackmail information is then revealed to exist just inside CAM′s head. Still, I cannot shake the slight feeling that Sherlock had to reckon with this possibility either – after he realised CAM′s spectacles are really just ordinary spectacles, he had to know about CAM′s true nature.
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I cannot live without brainwork. What else is there to live for? Stand at the window there. Was there ever such a dreary, dismal, unprofitable world? See how the yellow fog swirls down the street and drifts across the dun-coloured houses. What could be more hopelessly prosaic and material? What is the use of having powers, Doctor, when one has no field upon which to exert them?