My Young Son

My son is only 11 years old and about a year or so ago he started saying he sees thing. He started with mean looking trolls on rooftops with spears. He now says he sees very tall dark figures. He sees them day and night, at home and away from home. He says some times he sees a big black spot with white dots that takes away the trolls. He doesn't know what this black spot is but it seems to protect. He says they scare him. The trolls sometimes throw the spares at him but they disappear in the grass. The trolls only seem to be outside but the dark figures can be any where. He has even seen them at school. He became afraid of the dark very suddenly around age 3- 4 and I have wondered if it is because of this. I don't think the dark figures have ever seemed to try and scare or harm him in anyway. I haven't ever heard of anyone seeing trolls and maybe that is just his way of explaining it. I have been told that maybe he needs to see a doctor about what he is seeing. I don't believe that my son is mentally sick. This has caused break downs at school and for a 5th grader that is the worst. He even asked other kids if they seen the same things he was seeing for them to make fun of him. This being said I need help and I don't know where to turn. I feel that this is spiritual. I as a child seen a spirit but nothing like this. I need to know how to help my child. I need to hear that someone else has had this kind of visions. Any input on how to help my son would be great or even if you have just experienced the same kind of visions.