I spoke with the school counsellor yesterday.

She believes strongly hat Evan is dealing with Anxiety.
We suspected he did have some level of anxiety issues but she has confirmed it.
She thinks that the reason we are getting reports from his teachers that he is doing well in class, is settling in really well, enjoys school etc. While at home we get extream mood swings & angry outbursts is because he is working so hard to keep it together at school,then coming home mentally exhausted & just loosing it.
He isn't old enough to really understand these feelings he is having so just lashes out.

So we are on the path to helping him.
We had already started this path for the anxiety that we had seen coming out in him (obsessions) but have jumped forward a fair bit in realising its alot deeper then we had realised at first.
Now we have some "professional" help on our side that will help us help him.

It also helps me remain a little more calm knowing the reasons behind his behaviour.