Five year old throwing violent tantrums

My five year old son started kindergarten in September with all new kids.  Every night either at bedtime or in the middle of the night, he will throw a violent tantrum, sometimes lasting more than an hour.  He will hit, kick, scream, and bite me (his mother).  Almost like he is in a trance.  There's no talking any sense to him when he is in the middle of one of these.  I've given him snacks during the day to make sure his sugar level won't get low.  We've tried putting him in his room, nothing works, he just gets more upset.  We can hear him screaming from outside the house.  I try to put my arms around him and he pushes me away, i try to leave the room and he wraps his whole body around my leg so i can't leave.  I don't know how to react to these.  We also have a 2 year old daughter and she doesn't throw half the tantrums my son does.  At school he is a great student, doesn't throw any tantrums or hits anybody in public.  This only happens at home and at night and mostly with me, not his father.  I thought this was just a phase with him starting kindergarten, but these episodes are getting more and more violent.  I don't know if he needs a counseler, if something medical is going on.  I'm very worried.

[margypops]

He could be getting night terrors, that causes him to wake in the night screaming.Has there been anything new happening in his life ,does he like Kindergarten you say he is a great student but when he is at home there are these behavior issues. He has a 2year old sister, could he be jealous of attention she gets .? As they seem extreme tantrums I would say yes some counseling would be in order to get to the bottom of why he is suddenly behaving in this way .good luck