The incident occurred during the Sharks' 9-2 rout of the Rangers on Tuesday when Stuart was initially assessed a minor penalty.
Nash, who has a history of concussions, said he felt the effects of the blow.
"I have a headache," Nash said. "It got worse. I'm concerned the way it feels."
The game was Stuart's season debut after he missed the opening two games with a lower-body injury.
He will be eligible to play again on October 17 when the Sharks visit the Dallas Stars.