Asbergers

Hi, I'm new on here and tearing my hair out!
My little boy is 3 and a half and I have never thought there was anything different about him. He is incredibly boisterous but people have always said to me 'he's a boy, that's what they are like'.
I am so worried about him because he can't make friends at all.
He has been at his current nursery for about 5 weeks now and they have already had people in to observe him because he has been aggressive toward the other children. This is something I have never witnessed and I have no idea where it has come from. He is not at all shy and will always talk to children when we are out and about so I find it strange when we are told that he isn't socialising.
I have been told that some of the children are now frightened to come to nursery because of him. I am so upset about this and don't really know what to do. I can honestly say that he just doesn't behave like that at home.
The previous nursery he went to decided after 3 sessions that he was either autistic or had Asbergers, (they decided this because he was sorting out lots of blue things one day)
We sent him to a nursery for children with learning difficulties and he absolutely loved it there. The staff were amazing as were the facilities. We have had to move him though because they do not feel that he has any learning diffculties.
He seems to be quite happy at the new place and doesn't seem bothered when he tells me that the other children have told him they don't like him.
It breaks my heart because he is so caring and loving.
We keep being told that the 'problem' is that he is too clever?
Has anyone else had this problem? I am so upset about it and don't know what to do next

HI there hun, what can I say but hang in there, I had very similar problems to yourself my son Josh who is five could be very contoling and aggressive,yet is very caring and loving at times,Josh has just been diognosed as ADHD and we are now looking into getting him statmented for support at school.If you are still getting no joy then maybe you can speak to your health visitor for advice.Hope you find a way through, but remember he is your little man and is worth fighting for, the help is there it is just tough to get it sometimes due to funding and stuff. keep your head up and dont hesitate to message me if you want to talk some more! kel