Monster in winter and blue dots
I read a kids or teen book a while back about a boy who is being hunted by this monster in a place that's very cold. Maybe it was winter?
I distinctly remember he had a blue dot almost like a pen mark on his hand and so did the other people were being hunted by this monster.
At some point there's a scene where he's talking to an older man who has been running from this monster for years who lives in a trailer and eats dog food.