Can anyone tell me what happened?

In biology cl, everything seemed to be fine. my friend was sitting next to this boy while they were talking about bodily fluids (i wasnt there, but the nurse told me wut happened) out of no where, his eyes were closed for like 5 minutes straight. all of a sudden, he just falls off of his chair. while he falls, his leg pulls down the desk on top of him. then his eyes roll into the back of his head, he starts to shake slightly, and his eyes were REALLY red (not his actual eyes, remember his eyes were in the back of his head). then he was taken to the hospital. everyone was really wondering wat happened and they were arguing. he wasnt drooling or anything, just what i explained happened. so what could it have been?