@BillRM,
He knows you love him - keep giving him scritches and lots of strokes and I think you'll know when it's time to let him go...
I had my cat put down on a day that he wasn't so poorly. He'd had 2 surgeries on his ear which had been removed and tumours growing out the side of his head and his face was all pulled together, deformed, and getting tighter byt the day causing him to twitch a lot, like little fits. So... one day, after he'd been twitching quite a bit for the few days before, he was sitting on my printer and looking at me as I was working and I thought... now's the time, when he's not in pain... he twitched at me, kinda smiled to let me know it was time for him to sleep, almost gave me permission.
I called the vet, he came to my home within half and hour and my PaPa came out just after the vet had put him to sleep and he took his last breath pain free and in my arms and then we waited for my eldeset son to come home and PaPa buried him in the paddock.
Broke my heart. Right decision for my kitty tho.
Give Blue Eyes lots of love and I do hope for y'all he will improve over the next few days.