I have also heard it said - better too soon than too late (from Souffle
) and I personally now accept that, hard as it is for us, helping them on their way at the end is a kindness if they are suffering. They just go to sleep. I had to take Newt to be helped on his way and I perhaps should have done it a little bit sooner.
You could try putting some baby food on the end of a small teaspoon and see if he licks it off. If he doesn't then he doesn't want to eat and that is because he is dying and he is ready to go. So if you talk to him and tell him you love him and it's ok to go then maybe nature will take its course.
With Charlie - this stage took such a long time that I had to take him to the vets in the end as he was trying so hard to go but didn't and had a prolapse.