So sorry to hear of your son's horrid dream/demonic experiences.
Do you have any crosses or crucifixes anywhere in your house? Perhaps placing one in your son's room with a tea -light in front would help?
Also, do you have any Christian Worship music? Played softly constantly, in your son's room might be helpful?
Does your son play any violent videos games? music videos? Is he being bullied at school? (just thoughts...)
Get some water, and Pray Over It, saying, Bless this water O God, in the Name of Jesus Christ and of His Precius Blood shed for the sins of the world.
Then, go up and sprinkle this water in every room in the house, saying, By The Blood of Jesus, you devil get out of this house. etc. etc.
I will pray for you also, I wish you well my sister, love edwina.