Thanks to everyone for the replies
Cedric has been treated prior for parasites (giardia, trich and corona virus) which were found through specimen examination. The medication that was given to him (and his brother as a precaution) seemed to help until 10 days ago when it started again.
They are nearly 7 years old, and all that I know about their previous life is that C. was "faecal incontinent" so was LOCKED in his litter tray until he performed in it. I assumed initially that his litter tray avoidance was due to this experience. The vet seems to think that the stress of this is what has caused his problem - that and no treatment for the infection. I feel so angry.
They were both on dried food, and I'm gradually introducing wet with both. Albert has accepted and adapted well - a little tummy upset at first but nothing serious: Cedric is the worry.
Nothing has been said about a biopsy yet - my vet wants to monitor the effect that a steroid shot has on him - we go back next
Monday. I'll post how we got on.
Just as an aside - have you heard the saying "the light's on but there is no-one at home " - that's Albert
I'm assuming he wasn't treated too well either. But he and his brother are so affectionate and loving I'm determined to see this through.
Thanks again
Draco