Flapping of arms

My son is 7 yrs old...nearly 8 after the New Year... he has been showing signs of ARMS FLAPPING... this condition has only come about more recently...he can be watching a movie or playing on a game...or anything that gets him excited...he jumps around and starts flapping his arms...and jumping around....he does not care who is in the room ..he will just get up and do the actions...
I have noticed if i take my son the pictures...especially 3D ones...he gets so excited...there is no one else there but him...lost in his own world...if i can put it that way...its like a one track mind thing..unexplainable.
I must admit as a parent ..i have had 4 children already...and my 7 yr old is my last child...
Myself , and my daughter and his grandparents ...used to laugh when he got up flappng and so excited... like he was in the film he was watching.....
Till i was on my night shift at a charity place for children..and i happen to bring the flapping of arms up....and was told it was a sign of autism...
I know my son has been alot different from my other 4 children...he is really more sensitive..and very caring and loving...in school great at maths etc...but spellings...we could learn them all week ...then on the day...how many he gets right ..well...
His teacher thought he was dyslexic...after all this time ...so introduced..coloured plastic ...to read the words..but come on dialogue etc..to learn at 7 year old ...for gods sake...
Thanks to the Nurse were i was working...this has given me some insight to me ..as she said ...arm flapping was a sign of autism...I just want to say THANKYOU...to a member..from a charity organisation....a place that does care....xxx

[Athena_M]

Yes it is a sign.  My son has mild autism.  He will flap a lot when he eats candy like skittles.  We ae doing no food dyes Feingold diet and the flapping goes down.