Thanks Hélène, it's not a new injury - I hurt it falling downstairs some weeks ago and it's still bothering me. The doctor said that depending on whether there was a hair fracture it could take anything up to ten weeks to get back to normal, so I just have to be patient!
Because stitching for too long hurts it I thought I'd try crochet instead, and that turned out to be a bit of a mistake.... So back to sensible stitching

!
The stitch design isn't mine, by the way - I found it online and liked it, but so far hadn't actually tried it. I'm still working on ways to minimise all the fastening off and on though *sigh*