Fortunately it's not a running day for me - but today I've been suffering rather astonishing after-effects of yesterday evening's triumph! An hour or two after I got back and changed, I noticed an itchy rash on both arms. This then spread over the next while until it was over most of my body and thighs as well. A piriton just about dulled the itching enough that I could get to sleep, but I then woke every couple of hours through the night, so uncomfortable that I couldn't get back to sleep until I'd got up and put lots of cold water on it to cool it down for a bit.
So I've not been to work today, managed to see the doctor this morning (yay for our local surgery!), have been advised that it's definitely some sort of allergic reaction (possibly triggered by heat or sweat, nice!), nothing contagious. So that's sort-of good news - I'm not about to give anything nasty to Mr Rainbow with his compromised immune system - but also sort-of bad news, as I'm hoping this doesn't happen again after my next run!
In future, I'll have to make sure to have a more thorough cooling wash when I get back, but am really hoping this is a random one-off... I thought I was past the stage of considering myself allergic reaction to exercise!