ST. LOUIS — The NFL is investigating whether correct concussion protocol was followed for Rams quarterback Case Keenum late in Sunday’s loss at Baltimore.

A league spokesman says Monday that a review was begun after the game “to determine the facts of the injury … and why (Keenum) was not removed from the game for the necessary evaluation by a team physician or the unaffiliated neuro-trauma consultant, as required by our concussion protocols.”

That review is continuing Monday through discussions with the Rams and their medical staff, the ATC spotter, game officials, NFL medical advisers, and the players’ union.

Meanwhile, the NFL plans to reinforce the procedures for this week, with three games scheduled for Thanksgiving Day.

The back of Keenum’s helmet slammed into the ground.

His hands immediately went toward his head, and he struggled to get up, appearing staggered. But he stayed in the game.

JETS: New York is sticking with Ryan Fitzpatrick at quarterback despite the team losing four of its last five games after a 4-1 start to the season.

Coach Todd Bowles says Monday that there wasn’t much discussion as far as making a change to Geno Smith at the position.

Fitzpatrick threw interceptions to end each of the Jets’ last two drives Sunday in a 24-17 loss at Houston.

• Darrelle Revis’ concussion symptoms have not improved a day after injuring his head against the Houston Texans, leaving the New York cornerback’s availability for the team’s next game in doubt.

Center Nick Mangold is also uncertain after needing six or seven stitches to close a deep cut on his right hand. He was hurt in the second quarter and remained on the sideline the rest of the game with his snapping hand heavily wrapped. Bowles says an MRI was negative.

• New York waived outside linebacker Quinton Coples, the team’s first-round draft pick in 2012.

RAVENS: An MRI has confirmed that quarterback Joe Flacco tore the ACL and MCL in his left knee in Sunday’s 16-13 win over the St. Louis Rams.

It’s a season-ending injury, so Matt Schaub will start next Monday night against the Cleveland Browns.

PANTHERS: Carolina plans to activate defensive end Charles Johnson from short-term injured reserve on Tuesday. Coach Ron Rivera said he expects Johnson will play on Thanksgiving Day against the Dallas Cowboys.

Johnson will take the roster spot of backup guard Amini Silatolu, who tore the ACL in his left knee in Sunday’s 44-16 win over Washington and will be placed on injured reserve.

TEXANS: Brian Hoyer is done with the team’s concussion protocol and will start for Houston on Sunday against the New Orleans Saints.

Hoyer was injured early in the third quarter on Nov. 16 against the Cincinnati Bengals and sat out on Sunday against the New York Jets.

Colts: Left tackle Anthony Castonzo has sprained the MCL in his right knee and is listed as week to week.

GIANTS: The bye week went better than expected for New York.

Philadelphia and Washington lost and the Giants (5-5) returned to work Monday with a one-game lead in the NFC East with six games left in the regular season.

New York’s first playoff berth in four seasons is within its grasp despite a season of ups and downs.