Sounds very much like a seizure - Im a special education teacher and child psychologist, and have dealt with seizures that present in a multitude of different ways. This behavior is not normal, and very suspect - even if it isn't a seizure, something neurological is most certainly going on (it could be anything from brain chemistry thing to a glandular problem). Whatever the problem may be, and I would get him an appointment RIGHT AWAY with your ped - and stress how much of an emergency the situation is to the receptionist/nurse/doctor so that they don't put you off as just another anxious mother. I would suggest you not take him JUST to the pediatrician, but have your ped refer you to a pediatric neurologist - in cases such as this, a second opinion from a very specifically trained professional is necessary. Often pediatricians do not have the in depth and specialty training to deal with neurological issues.
I don't know if you are local, but Lucile Packard Children's Hospital and Stanford has an AMAZING pediatric neurological department - if your medical insurance allows, I would ask specifically for a referral to a doctor there before anyone else. I did some of my training/masters studies/psych internship there and can vouch for the above and beyond excellence of their doctors and staff.
