Pead recommendations for Brisbane North!

Hi, I am hoping you could post this anon for me? I am desperate and needing help!
Hi Im's, I need advice ASAP! I apologise for the long post! I am a single mum to 4 cherubs, mr's 9,7&5 and miss 3! I am struggling with mr 7, when he was 3 he was seen by a pead, because his behaviour was abnormal (hyperactive, full on, naughty etc), the pead spent 15 min with him and said he is a normal boy! Nearly 5 years on and OMG, he suffers from panic attacks over very small things like being late for something, or having pen on his homework (which he purposely did) etc. he also suffers from anxiety! He has always been rough with his siblings, but lately he is attacking them (hitting, kicking, tackling etc) and only a few weeks ago threatened them with a knife! He has also dangled miss 3 by her legs off a top bunk all because he didn't want her up there with him! He laughs while doing all of these things like he is totally enjoying the thrill! He also likes to hit and kick walls, windows and doors if things aren't going his way or his routine is out! He can't handle a routine change even in the slightest way, just recently he had a few BIG public out bursts all because of a routine change, this is very abnormal for him to have an out burst in public infront of strangers! He is a very bright boy who does very well at school academically and in sports! This is where my problem is, he hasn't had an outburst at school yet, he has come very close but his teacher saw him working himself up and she defused the situation quickly! No one wants to see him or asses him because he does well academically and he behaves at school (even though it's starting to creep in). I am a teachers aide and I am well aware I am possibly looking at him being ASD, but I need to find a pead that specialises in this as my son hides this behaviour from strangers (which isn't uncommon for ASD kids). His panic and anxiety attacks are full of tears, yelling, screaming hitting, kicking, fast breathing etc and can last for 2 hours at a time. His teacher has said she can let him have an outburst at school to help me support my case, but I can't allow that (even though I know she would have it under control) for fear of the other students but I know whether I allow it or not, it's going to happen eventually! My son hides this violent, frustrated, confused side very well, but at home he has his siblings petrified of him 95% of the time and to be honest he frightens me too! He can be a very sweet loving boy at times, and usually he can't remember what he has done! When he does remember he apologises after he has calmed down and says he just doesn't know how to control himself when this all happens! As I said before, I work with children, and the behaviour he is displaying at home I see in some of the students at school, I realise I am dealing with more than the above mentioned panic and anxiety! I need a great pead who specialises in this, my gp thinks he should be medicated, but she doesn't know of a pead that she can recommend, I am more looking for answers so I can help my poor boy! I also am aware his hormones are most likely kicking in, but this is beyond normal! I am located on Sunshine Coast/ morayfield area, looking for public or private recommended peads! This is taking it's toll on me, i work, study, full time single mum to 4, and I am mentally drained by the stress of my poor boy :-( thankyou for any recommendations for peads!