It is just an upper respiratory most likely. Use a warm wetwashcloth to remove the crush and gunk. Have the neighbor come see the kitten, don't take the kitten to him, don't separate the kitten from the rest of the litter. He may need antibiotics, I usually don't give any, I let the illness run its course and continue wiping the eyes and making sure the kitten is nursing. But that's just me. If your neighbor vet is willing to help, I would go that route, taking them all to the vet will just add stress to the mix.
Also, if the momma cat keeps moving them to places you can't get too, you need to confine them to a quiet room, laundry room, bathroom or even a large dog crate until they are a little older.
Also, if the momma cat keeps moving them to places you can't get too, you need to confine them to a quiet room, laundry room, bathroom or even a large dog crate until they are a little older.