pcantona

Yeah I know exactly what it is. It is epilepsy!
My older sister has this, she did exactly the same thing when she was a kid and still does the same thing 20 years later if she doesn't take her med's.
You need to take your son to a doctor and have scans done on his brain and get him on medications for epilepsy. My sister does/did exactly the same thing, you can carry a conversation and she can just fade out with eyes all glassy and droopy and not respond to what you are saying and then 10-20 seconds later be back to normal and she is not aware of it herself, you can tell her, hey you faded out and she can be "I did not, what are you talking about??". The person itself is never aware of this. It is called "petit mal".

But when she got in her teenage years she also she got worse episodes than that(grand mal), when she gets the trembles too, screaming of pain, arms popping out of its sockets, stop breathing, biting on the tongue etc. It is extremely dangerous if it is untreated, so you need to go to a doctor ASAP.
In itself it is not lethal, but it can have serious consequences, your son can cross the street and "fade out" and get into an accident etc. There are 2 versions of epilepsy. Mental and from brain damage. From brain damage is the most common. It is usually from child birth, when if your baby does not start breathing right away after child birth or suffered from oxygen loss while in your womb, you get brain damage. My sister has no brain damage at all, she has emotional/mental epilepsy. It is from the brain neurons being over-sensitive. Best thing right now for you, is to NOT make him upset, make him sleep a minimum of 8 hours a day, make him go to bed early and keep him calm.