BUFFALO, N.Y. (WIVB) — It was a stunning moment in Thursday night’s game between the Miami Dolphins and Cincinnati Bengals when Dolphins quarterback Tua Tagovailoa was slammed to the ground after taking a sack. His head hit the turf and his hands and arms immediately seized up.

Tagovailoa was taken off of the field on a stretcher.

The scene took place just four days after Tagovailoa suffered an injury following a hit from Bills linebacker Matt Milano in the first half on Sunday’s game. Many observers, including UB Concussion Management Clinic Director Dr. John Leddy, believed the hit resulted in a concussion. However, Tagovailoa was allowed to return to the game, even after stumbling to the ground in the seconds after the hit. The Dolphins said Tagovailoa was evaluated and the fall was caused by a back injury. The NFL Players Association began investigating the claim on Sunday.

Thursday’s follow-up injury is raising questions about the NFL’s concussion protocol and if the Dolphins followed it or not.

The NFL’s protocol states that an independent neurological consultant evaluates the player in the training room right after the injury, including asking questions about symptoms and observing behavior.

“They say he passed the questions and the physical examination. I guess the point that most people … are concerned about is that the initial observance of his behavior suggested that he was concussed,” Dr. Leddy said. “Even if he cleared up in terms of his symptoms, the protocol to protect him would have been to take him out of the game.”

In the seconds following his hit to the head on Thursday, Tagovailoa’s arms and hands went into what is known as the “fencing position,” which usually indicates a severe concussion or a “stunning” of the brain and spinal cord. This can happen when someone is knocked unconscious.

“It’s involuntary, but it’s one of the signs that we look for, much like the unbalanced gate he had four days earlier,” Dr. Leddy said. “The point is, even if he said he had no symptoms and he had a fairly normal neurological examination after that first hit in the Bills game, his initial behavior suggests he had a concussion.”

Dr. Leddy said that this type of injury can slow his recovery considering that this would have been his second head injury in four days.

“Given what happened to him within four days of one another, he’s now at risk for having a much more complicated and delayed recovery from this second injury than he otherwise would have had he been protected the first time,” Dr. Leddy said. “Instead of missing a game or two, he’s at risk for missing multiple games and maybe large parts of the season.”

Dolphins head coach Mike McDaniel said postgame Thursday that Tagovailoa had been diagnosed with a concussion at University of Cincinnati Medical Center, but nothing more. He additionally said that they had been testing him daily throughout the week beforehand.

The NFLPA tweeted shortly after the injury: “Player health and safety is at the core of the union’s mission. Our concern tonight is for Tua and we hope for a full and speedy recovery. Our investigation into the potential protocol violation is ongoing.”

Tagovailoa did fly home with the team in the hours following the injury, which Dr. Leddy was not concerned about. It is still unclear how much time he will miss.

You can watch the full interview with Dr. Leddy above.