Well, neither the vet nor the (expensive!) blood test could find anything wrong. The vet said it could be nausea and gave her an injection for it, and Drum really perked up later and was pretty much back to her old self by bedtime.
However, about 20 minutes ago Bass started retching and gagging while she was eating. I've just had to follow her around the house, mopping up little pools of sick
and trying to keep her off the bed!
She seems to have calmed down a bit now but is still gulping very slightly - possibly her throat hurts after all the retching.
What on earth is going on? Some sort of retching virus?