Okay, everyone.

So, there's this kid that's afraid of the dark. At one point in the movie, he gets to see a old doctor about it, and later on, his mom and the boy goes to some hospital or something or a basement. Anyhow, the doctor forces him inside a closet or a room, with no lights on of course.
And supposedly, the killer is in there with in. But, in the end, it was all in his mind. Or at least that's what the doctor though. Or the phsycologist.

Anyway, if you have any tips, even if it was a thriller, help me! Anytthing is appreciated

Some parts of it sound like " The Sixth Sense" and some parts of it don't. Also "The Sixth Sense isn't a horror it's a thriller. So I'm not sure if that's what your looking for but I think that's probably it.

I'm thinking Boogeyman.