What a sweet little fellow, and we would check with the Vet as to waht you can give him. If they are close enough you can drop in, and ask if they can giive you something temporary for him, although they usually look at the Kitten first.
What a little Love Bug, and The Found Cats all pray that you fail fostering and make him your very own.
Moose Angel will be his Guardian Angel.
Here he is a few years ago with John Hancock.