In the meantime there are antibiotics and I have (with dalekboy's assistance) laid in food supplies.
What I thought (yesterday) was a lump in my right leg is apparently a subcutaneous* boil/abcessy thing. Watching the infection spread up the leg in a line has a certain grotesque fascination.
I've been ordered off work in the meantime to let the immune system kick in.
*Mostly, The skin is now going quite pink
So, plenty of rest and fluids for me over the next day or so.