Still Can't Nod (But Tries!)

The twins turned 3 over a month ago and T still can't nod his head. He is ... YAY! ... finally getting the hang of Yes and No, but although he tries, he really CAN'T nod his head. I have been trying to help him do it and it's hard even with me helping him. I'm actually wondering if I should take him to an orthopedic specialist. He somehow picked up how to grimace not long ago, and you should see the poor little guy trying to nod. He just stands there with this grimace on his face and his head moves about a millimeter. Now that he's picked up this grimace, and I actually tell when he's trying to do it, and I'm amazed that he occasionally has tried to nod at me the last couple of days even when I didn't ask him to! (wow!) But the poor guy just can't do it (yet).

He had difficulty learning how to shake his head too. I spent a lot of time physically moving his head back and forth, but once he got it he really loved it and he sometimes even uses this now to express no. (yay!) I guess this is part of the hypotonia.

T had the typical unusually large head for the first 2 years, and I wonder if this just made it too hard for him to move it? Leading to those muscles just not getting used. I wonder too to what extent that the delay in these basic gestures (the head shaking/nodding) contributed to the delay in language?

I don't really know what all nodding might be good for now that he's learned how to say Yes. Maybe I should focus on something else instead. But my instinct tells me that he should be able to nod. I think it somehow be more important that it seems.