6 year old strange finger twirling and neck movements

[Cindy0987]

Hello I have a 6.5 year old boy who has suddenly developed some strange movements. He started with doing a head nod to the side and that would happen several times a day. Now he has started to twirl his fingers around and then lift his arm back when finished. It's bizarre. I've sat with him and have held his hands and I can feel them just constantly moving. It's really distressing as I don't know why he has started to do this. He's always been a lively child and can be quite full on at times with tantrums etc. Could he be autistic? I'm not sure what to do or why this has come about.