I'd been feeling rotten and in a lot of pain for a day or two, rotten enough for my G.P. to call an ambulance and send me to Accident & Emergency. Horrors! It transpires that I am suffering from an attack of shingles. And "suffering" is the appropriate word, it's bloody painful. Extremely painful.
I dimly remember learning about shingles at nursing school. Shingles (stupid name!) is caused by the same virus that causes chicken pox. After the chicken pox has gone, the virus stays in your nervous system in a dormant state. Years later the virus can become reactivated, as shingles, not chicken pox. And what a joy it is.
There is a shingles vaccine, I've discovered. It's not readily available in New Zealand and it costs a few hundred dollars according to my G.P., but I wish I'd known that because I would happily have paid a lot of money to avoid what I'm going through now!