My best friend in middle/high school did that (I witnessed it a few times at slumber parties). We talked about it many years later. We all thought she was faking to try to freak us out or to be funny. No, it was real. She has dissociative disorder and PTSD. I really can’t say what happened to her because it is too triggering.

Of course, you should see a therapist and psychiatrist to diagnose your symptoms.