Thompson left the game with a lacerated ear after being accidentally kneed in the head by the Rockets' Trevor Ariza in the fourth quarter. He was cleared to return but began not feeling well after the 104-90 win that lifted the Warriors to the NBA Finals, according to a statement released by the team.
"Klay Thompson was evaluated by the Warriors medical staff immediately after suffering an injury during tonight's game and was put through a concussion evaluation," the team said. "At the time he did not show any concussion-like symptoms. After the game he began to not feel well and developed concussion-like symptoms. He will continue to be evaluated by the team's medical staff tonight."
Thompson said in a televised postgame interview that he was "feeling a little dizzy," before adding, "We got a week off -- or close to it. I'll be all right. I'll get my health back."
Thompson must pass the concussion protocol before he can return to play. The NBA Finals start June 4.
Thompson's injury occurred when Ariza, caught in the air on a shot fake, hit the right side of Thompson's head with his right knee. Ariza was called for a personal foul on the play.
Blood coming out of the cut prevented Thompson from checking back in to the game upon his return to the Warriors' bench. He ended up needing three stitches to close the wound.
"He was definitely shaken up. We'll evaluate him tomorrow. It was a bizarre night for him," Warriors coach Steve Kerr said in his postgame news conference before Thompson's concussion-like symptoms were revealed. "Huge first half that really got us going, and then I left him in too long, he got his fourth foul and I thought I'd buy one possession, see if we could get him a shot, and when he picks up his fifth and when I do bring him back, he immediately gets hurt and out for the rest of the night.
"The break will be good for him. It'll probably be good for all the guys with the run we've been on, but especially for Klay."
Thompson finished the game with 20 points.
Information from The Associated Press was used in this report.