A Silhouette in My Mirror

Two nights ago I caught a glimpse of a grey silhouette in my mirror.  I was very tired and told it not to bother me because I was not in the mood for talking.  So for the last two night my son has gotten up in the middle of night to sleep with me because he is scared.  He never does that.  It makes me wonder if he is afraid because the spirit is talking to him and he doesn't know what to do.  I explained to him to use his Faith, pray about his Fear and then tell whatever it was to go away and let him sleep.  He doesn't believe me that he has that power. I don't know how to get through to him.