He went off eight minutes from time, but subsequent medical checks have revealed no obvious damage.
Chris Mallac, Bath's head of physical preparation, has been in contact with England team doctor Simon Kemp, who will assess Grewcock further when the national squad report for duty in Surrey on Tuesday.
Grewcock won his 38th cap when England beat Italy eight days ago, but would appear to be in a straight selection battle with Ben Kay for the Calcutta Cup clash, given skipper Martin Johnson's impending return from injury.
"I spoke to Simon, and he will review Danny when he meets up with the England squad," said Mallac.
"Yes, he did sustain a head knock on Saturday and suffered from blurry vision, which is why we brought him off, but as of Saturday night, his headache had gone and he was basically symptom-free.
"The England guys will obviously keep a close eye on him, but as long as he suffers no recurrence of the headache when he resumes contact training later in the week, there should be no problem."