Tua Tagovailoa left Thursday night's game with another concussion, at least his third over the past three seasons.

The quarterback was hit on a scramble in the third quarter of the Miami Dolphins' 31-10 loss to the Buffalo Bills. He walked off the field under his own power.

Tua missed four games in 2022 because of concussions, plus the team's playoff game. His history with head injuries has led to several former NFL players, including former Dolphins teammate Ryan Fitzpatrick and Las Vegas Raiders coach Antonio Pierce, saying he should retire from football to preserve his long-term health.

Here's what we know about Tua's status and history with concussions:

What happened to Tua Tagovailoa

On a fourth-down play late in the third quarter Thursday night, September 12, Tua Tagovailoa scrambled up the middle for a first down. He dove into Bills safety Damar Hamlin with his head hitting the defender's chest and then hitting the ground.

Tagovailoa's arms froze in the air in what neurologists refer to as the "fencing response," a sign of head trauma. He was able to walk off the field and did not return to the game.

Tua Tagovailoa injury update

Tua Tagovailoa was diagnosed with a concussion shortly after exiting the field. He was set to undergo further tests Friday.

It is not yet known whether Tua would be placed on injured reserve, which would force him to sit for at least four games. Coach Mike McDaniel did say he would be doubtful for the Dolphins' next game, September 22 at the Seattle Seahawks.

Is Tua on the concussion protocol?

Tua Tagovailoa is currently in the NFL's concussion protocol. He has 10 days to clear the protocol before the Dolphins' next game September 22 at Seattle.

Here's what Tua will have to do before he is cleared to play again:

• Phase 1: Symptom limited activity (introduction of light aerobic activity)

• Phase 2: Aerobic exercise (more than 20 minutes of moderate to strenuous resistance)

• Phase 3: Football specific exercise

• Phase 4: Club-based non-contact training drills (participating in all non-contact practice drills)

• Phase 5: Full football activity (clearance)

Tua Tagovailoa concussion history

Thursday night was Tua's third registered concussion, though there is speculation that he had a fourth. During the Dolphins' Week 3 game against the Bills, the back of Tua's head hit the ground hard after a hit by Matt Milano. The quarterback stumbled while he got up, and he briefly exited the game. McDaniel said Tua was checked by an independent neurologist and was out of the NFL's concussion protocol the following day. The injury was initially announced as a head injury, but that was later changed to a back injury.

Four days after that game, Tua had an even scarier injury on Thursday Night Football against the Cincinnati Bengals. In the second quarter, the quarterback was slammed hard to the turf and he lay there afterward with his fingers seemingly frozen in the air for several seconds. He wound up missing the next two weeks after the Bengals game. (Warning: The following video may be unsettling.)

Ten weeks after he came back, Tua suffered another head injury against the Green Bay Packers on Christmas Day. He briefly exited that game before returning. After the game, he was diagnosed with another concussion. Tua would miss the last two games of the regular season, as well as the Dolphins' first playoff game since the 2016 season.

Will Tua Tagovailoa retire?

There's no telling how Tua will react to his latest concussion. He has said he considered retirement after his concussions in 2022. And former NFL players have said he should call it quits, from ex-teammate Ryan Fitzpatrick to Hall of Fame tight end Tony Gonzalez, from linebacker Manti Te'o to former star receivers Antonio Brown and Dez Bryant. Friday afternoon, Las Vegas Raiders coach Antonio Pierce said if Tua were on his team, "I'll be honest, I'd tell him to retire."

Repeated concussions have prematurely ended several NFL careers, including Hall of Fame quarterbacks Troy Aikman and Steve Young. Star Indianapolis Colts quarterback Andrew Luck also retired early because of the fair of lingering health issues from sustained brain trauma.

FAN VOTE: Latest Tua Tagovailoa concussion has fans asking if he should retire. What do you think?

But ultimately the decision is up to Tua. Coach Mike McDaniel said Friday "it would be so wrong for me to even sniff" the subject of Tua retiring. There are still tests to run, and time will tell whether and when he is healthy enough to play again.

“You’re talking about his career,” McDaniel said. “His career is his.”

Tua Tagovailoa contract: How much money would Tua get if he retired?

Before the season, Tua signed a four-year, $212.4 million contract extension that would keep him in Miami through at least the 2026 season and as far as 2028.

The Dolphins have paid him $43 million for the 2024 season, according to Spotrac. His contract includes $167 million guaranteed, according to Spotrac, so if Tua is forced to medically retire, he would be owed the extra $124 million. If he is cleared to play but decides to retire anyway, the team could void the $124 million. In that case, the two sides would likely reach a settlement.

Dolphins depth chart at QB

Skylar Thompson stepped in against the Bills after Tua left the game. He went 8 of 14 for 80 yards and was sacked once.

McDaniel said the team would look at signing another quarterback. Veteran Ryan Tannehill, who spent seven seasons with the Dolphins, is available as a free agent.

Here's a look at the Dolphins' quarterback depth chart:

• QB1: Tua Tagovailoa

• QB2: Skylar Thompson

• Practice squad: Tim Boyle

Contributing: Hal Habib and Joe Schad, Palm Beach Post; Chris Bumbaca, USA TODAY

This article originally appeared on Treasure Coast Newspapers: Tua Tagovailoa concussion history, injury status