I’m pretty sure one test would be for Feline HIV. As far as I remember with Snotcat (done when he   fell ill with a stomach thing that he responded to an injection for and then relapsed, and it turned out he had this), the blood tests were quite expensive.

Furball will be free until Wednesday evening. I don’t think he will like this but he will have to be kept in from then until the trip to the vets (unfortunately, Sheringham – I wish they operated in their Cromer branch which is under 10 minutes from here). With his movements over the last week or so, that should be ok.