This feels straight out of a horror novel. If I were writing your story, next the protagonist would start questioning their sanity, or find out the figure has some connection to their past. Not saying that's you, but maybe look into your family history? And document everything, could be useful …

Incorporate local myths into your story for more depth. Every culture has tales of mist or fog, often as a veil between worlds. Those lost within could encounter creatures or even become part of the fog themselves. And don't forget the psychological aspect - the isolation, the confusion... That's where …

Dreams are so wack, right? Teeth falling out can symbolize not just fear of aging but also feelings of powerlessness or loss of control in some part of your life. Might be worth taking a look at what's been bugging you or what's changing. Buckle up and face it head-on, …