I had quite bad arm pain for a few days after this, but it's gone now. Then today & yesterday I've been feeling shivery and generally unwell. Seems a bit late for a vaccine reaction given that it's a week since my jab.
Probably I have picked some other mild virus up, or it's just my body being funny.
(We did take my temperature and it's perfectly normal, which does probably suggest that it's just my body being weird, as I feel shivery yet emphatically do not actually have a fever.)
I've just taken a covid test to check it's not that, although highly doubt it as my mum had a negative test two days ago and she's the only person I could catch it from (I live with my dad too, but he rarely goes out).