Hmmm... I'm thinking feral. I don't think a tame kitten that young would do that. Where there's one kitten, there's more, if it wasn't thrown out of a car or something. If it wasn't, I wonder why it wandered away from the litter?... Mother dead maybe? Someone should check the tunnel. Anyway, poor kitty! I'm glad someone saved her. She's veeery lucky.
Very lucky indeed.