I am thinking that perhaps Clive left his former home because his previous owners refused to have him checked by a vet. And then it is possible that they were not aware of his condition. He probablay looked and acted like he was sick before and they either did or did not recognize his illness, but regardless, they didn't do anything about it. Cats have an inner knowing whether they are truely wanted or not. This possibly accounts for his coming to your home for his well being.

...........wayne