Please don't discount what your son has experienced based on those who simply can't believe in anything paranormal. Many of us have lived in houses where such things happen, usually experienced only by certain people. In one house, though, they were experienced by everyone in the family, while wide awake and all together in one room.
We don't bother to go into that with people, though, as the reaction is usually less than positive. Like was already said on this thread, if you've experienced it yourself, you know it's real. If you haven't, it's easily dismissed in any number of ways.
Doctors are not known for believing in anything they can't examine under a microscope. They'll most likely send him to a child psychiatrist who will put him on meds he doesn't need. Please use caution in taking this route. If you think something physical might be the cause, it might be wise to request a physical without giving the details you shared with us.
You may have a very special child who is more aware of things around him than most would be. He needs your support and understanding.
Good luck and God bless.
Susan