TAMPA, Fla. -- As Luis Severino recovered from his start in Game 3 of last year’s American League Championship Series against the Astros, the Yankees right-hander mentioned soreness in his right forearm, a comment that general manager Brian Cashman said that he disregarded when the issue seemed to dissipate.

When Severino’s complaints resurfaced during the offseason, the Yankees were concerned enough to have the hurler travel to New York on two occasions, though their MRIs and CT scans did not reveal any significant findings. Severino believed he was in the clear, but a new recurrence of that forearm discomfort has prompted the club to shut him down indefinitely.

“There’s an unknown right now,” Cashman said. “It could be small and a timing issue or it could be more significant than that, because we haven't determined what we're dealing with yet.”

Severino had been scheduled to celebrate his 26th birthday by throwing a bullpen session on Thursday at George M. Steinbrenner Field, but he is instead expected to travel to Orlando, Fla., for further examination by team physician Dr. Christopher Ahmad. That evaluation is expected to take place on Friday.

Cashman said that Severino has said he feels discomfort mostly when throwing his changeup, and he has been taking anti-inflammatory medication while throwing mostly fastballs and sliders this spring.

Yankees manager Aaron Boone revealed that Severino has a loose body in his pitching elbow that had, prior to these developments, been considered asymptomatic. Boone said that it is too early to tell if Severino will be ready for the start of the regular season.

“We'll see,” Boone said. “First things first is trying to get our arms around exactly what is going on in there, and then hopefully we’ll be in a position to get him going again.”

Severino signed a four-year, $40 million contract extension prior to the 2019 season, but injuries involving his rotator cuff and lat muscle sidelined him for most of that campaign.

He returned for three starts in September before making two more starts in the postseason, taking the loss in ALCS Game 3. Severino would have been the Yankees’ starter if they had forced a Game 7 at Houston’s Minute Maid Park. 

“I would say that the October issue was more of a low-level signal,” Cashman said. “He had mentioned a little soreness during his massage therapy as he was preparing for his Game 7 start. It was more of a throwaway comment, and during his routine before his next start, it completely went away. There was no issue. Therefore, it’s not something that was being followed up on.”

Cashman said that Severino again reported soreness before beginning his throwing program, prompting the Yankees to order an MRI in December. The issue resurfaced when Severino attempted to throw his changeup on flat ground, which prompted an MRI and CT scan that Boone said was “clean and consistent” with one Severino had in February 2019.

The Yanks endured a historic number of injured list assignments last season and are already down a starting pitcher while James Paxton recovers from back surgery, a procedure that is expected to keep him out until at least May.

“We're making evaluations and trying to get people ready for the season,” Boone said. “We feel great about the arms that we do have, and certainly in Pax's case where he's on his way back, I'm confident that it's going to be in due time. We'll just find out about Sevy, but it doesn't change anything about how we prepare, how we get ready or how we make evaluations.”

Jordan Montgomery was viewed as a front-runner for the fifth starter’s job, but a substantial Severino absence could open the door for the club to also consider slotting Luis Cessa, top prospect Deivi Garcia, Jonathan Loaisiga or Michael King into the season-opening rotation.

“I think we have a lot of people that would like the opportunity, I think there's a lot of people with a lot of capabilities and ceiling,” Cashman said. “You’d prefer to run your ‘A’ team out there, but I think we have a pretty strong ‘B,’ ‘C’ and ‘D’ team as well.”