The 10th-year UNC head coach spoke with Hairston in the locker room after the game.
"He said he feels a little bit better right now, but doesn't feel great by any means," Williams said. "He's pretty groggy still."
Hairston made his first four 3-pointers and added a pair of free throws to help UNC build a 38-24 lead with 4:16 left in the first half. On Boston College's ensuing possession, Eagles guard Patrick Heckmann drove the baseline with Hairston on his hip.
Senior guard Dexter Strickland collapsed to help from the opposite side of the court and collided with his teammate mid-air underneath the basket. T.V. replay appeared to show Strickland's elbow making contact with Hairston's head.
"I jumped up to contest the shot and I felt his face hit my elbow and my hip, and I just saw him go down," Strickland told reporters following the game, adding that he apologized to Hairston for not being in help position at the time. "I was hurt, so I knew it hurt him. But he's talking now. He said he's still a little dizzy and stuff like that, but hopefully we'll have him for the next game."
Hairston remained on his back following the play, holding his head until team trainer Chris Hirth checked on him. After a brief conversation, Hairston was helped to his feet by two Tar Heel walk-ons, but he was clearly woozy and slipped and nearly fell.
Hairston returned to a sitting position as referee Karl Hess asked security to bring out a stretcher. His mother, Wendy, joined him along with other members of the UNC staff while the Tar Heel players watched anxiously from the bench area.
"Seeing the stretcher come out and everybody not being sure if he's okay, and seeming him trying to walk and falling down, it was a scary moment," Strickland said.
An EMT inspected the back of Hairston's head as the stretcher was brought out. Play resumed once the Greensboro, N.C. native was rolled off the court.
Hairston has been at the center of a fan-fueled debate after he led UNC with 19 points in Saturday's loss at N.C. State despite playing just 17 minutes. He connected on 4-of-6 3-pointers over the final 6:23 in Raleigh before making his first four treys on Tuesday.
"I tell you what, he looked like he was about as hot as I've ever seen him in my life," Williams said. "We would have liked to have had him longer."
Hairston was not available for interviews after the game, although he was seen talking with his teammates in the locker room.
There was no further information available regarding Hairston's status for UNC's game against Virginia Tech on Saturday. For reference purposes, Reggie Bullock sat out the UNLV game on Dec. 29 with a mild concussion and missed a week of practice.