Well, another end result was a warning that sometimes, people who have problems with one shoulder get the same problem with the other a couple of years later.
This being a couple of years later, sure enough, my left shoulder started to hurt. It began in the summer, when my wife's twin habits of a) leaving open a window to "let in some air" which can be freezing at 3am, and b) pulling the entire duvet over herself so my shoulder was exposed to said freezing air, meant I kept waking up with a literally frozen shoulder in the middle of the night. I suspect, though, that it has a lot to do with my getting a new work chair which (unlike previous such chairs) has armrests. Sitting for hours with my left hand resting on the WASD keys and the arm on the armrest could easily have done it.
I have a different physiotherapist this time, Kelly. She's given me some exercises strangely reminiscent of the ones I got for my right shoulder, but others that are different (in particular, one involving pushing my left arm up using a stick). There are some new advances in the physiotherapy department, too: instead of getting just written instructions, I get ones with graphics. Here's an example:
If I were a woman able to do push-ups with my breasts, as the individual in the picture is, then this would be a breeze. As it is, though, I have to lie face down on the bed with hardly any space to breathe.
Oh well, let's see how it goes. So far, it's been agony...