That's so sad John.
Our dear Ripley became ill with kidney issues when he was only three or four, and the food and tablets he had just went to waste every day!
Sorry to say, but it ain't going to get better, much as we doted on our beautiful little boy, as much as you do...
You're a very caring man - you did the same for another 'stray' cat the other year, which was amazing, so keep strong!