Here's a terrifying little animated short film There's a Man in the Woods, by Jacob Streilein. It might make your head spin.

The YouTube version above has redone the vocals, which I think adds an extra element of tension to it. Below is the original from Vimeo.

There's a Man in the Woods from Jacob Streilein on Vimeo.

He notes on here that he based it on a childhood experience. You also find credits for the excellent score.