This is one of those tragic situations of not listening to your pet in time. I got Spencer II out of the pound four years ago - my alpha cat and successor to Spencer I (in my avitar). Recently he had been scratching himself. Less than a week ago he started to go downstairs and withdraw....got me concerned a couple of days ago. He had to have been infected. Then I saw he had more than a few fleas and was moaning last night. Tonight I went to the pet store to get flea products only to return to Spencer's lifeless body. Even for cats, this was a quick death spiral. Very sorry I did not wake up and act sooner. I miss you big guy already.
Oh, so very sorry to hear about Spencer and your loss! We've lost several cat buddies over the years and it is never easy. My condolences.