I sympathize, I had 2 guinea's that passed when I was younger. When 1 passed the other couldn't go on living and passed a day after.
Yours isn't giving up, so you can't either. Your doing the best thing for him right now, which is making sure he knows that he's loved.
I hope you can find a vet that makes house calls.
Maybe a painkiller thats mild enough to help him out? maybe a regular strength motrin, crush it up and dissolve it into water.
We do this for my dog, it seems to work well. But I have no idea if it'll work for pigs. (Im not a vet OR a doctor)
All the best, this is a tough time. Be strong, your pig needs you to be.
PM me if ya need to talk,
Jedi Wiggles.