On the last day of January, I was tidying up after a meeting, and I started to feel unwell. Having just eaten lunch, I reckoned it was a spot of food poisoning. I managed to make it home without incident, sent my spouse to the symphony without me, and went straight to bed, hoping that I would wake up, be violently ill, and feel immediately better.

However, by the time he got home from the concert, the general pain in my stomach had migrated to the lower right quadrant of my abdomen. I told...