5 year old clicks and screams out continually

My five year old son has this daily behavior where he screams out random sounds over and over until we tell him to stop. Sometimes he will do it again, once or twice even after we are looking at him and asking him to stop, and then immediately says sorry, but he yells it...I'M SORRY, I'M SORRY, over and over until I hold his hand and say use a quite voice. He also clicks his tongue or his mouth, or snaps or bangs on stuff excessively and repeatedly while watching tv, drawing, or gaming often switching between any of the above mentioned things. He has twin autistic step brothers that are 8 and at first we thought he was doing it to get attention and because the boys don't like it, he gets negative attention from them when they yell "BE QUIET!!!!) while I do believe sometimes it is done on purpose to instigate, most of the time, they are at school and he is alone and doing it.  He shows no other signs of any other behavior problems. He is extremely smart. He is already reading, computing math problems, some of them two digits, all in his head. He never stops talking, except when he's clicking. He's always asking questions about everything, and when we give him and answer he has to think about he starts pacing and clicking.

Should I be worried about this? He has two older biological siblings that do not show any of these symptoms, so I am at a loss.

Thanks

[dollyn]

To me it sounds like you should get your son in to see a Neroligest and they should do a EEG and run some blood test on your son.And they may even send you to see some other doctors also.

[Alexandria94]

I used to do the clicking when I was little, and it got worst as i grew older, but I did and still do hide it. the only thing that I can't control is that I always just blurt out yelling, even in the middle of class, but my parents think i'm doing it just because. But i'm not. I think you should take them to the doctors because I want to, but i'm affraid of how my parents would react. And it never hurt to be cautious!

[benjimom]

sounsd stressful. I would ask your pediatrician about it.  It might not be something he can control.

[boygirlboyboymom]

Our four year old son was on Adderall (adderrall) and started doing a scream followed by a lip trill like a tic he had never done before. It stopped when his Dr changed his medicine to Concerta.