This all sounds vaguely familiar: our god-daughter went through something similar from ages 2-11, and it turned out to be some sort of epilepsy (which ran in her family). She would not have full blown grand or petite mal seizures, but would kind of go "blank" for a few moments - anywhere from a few seconds to a minute or so. Sometimes she would stop in mid-sentence and just sort of stare into space, and then continue on a few moments later. Often, she would feel very drained after these episodes. Her mom mentioned that she used to do this after some hard crying, when she was very small. I'm sorry, I don't remember the name that they gave to this condition, but I can find out if you like. I do know that it was classed as a type of epilepsy, and that she has - at age 14 - outgrown it completely! I hope your son's tests go well; our daughter had to have an MRI at age 2, and I can remember how stressed out I was about it. I will pray for you both - please let us know how everything turns out.