It's much better this morning! That's good because I have an irrational fear of waiting rooms.
The swollen calf has come down a lot and the bite area seems to be less angry, although the blisters are still swelling delightfully. I can walk properly again too. Quite relieved because I'm on holiday this week, and really didn't want it spoiled by a dirty beaked midge.
Thanks for all the concern/advice/warnings of imminent death/mutation.