ANAHEIM, Calif. – Keibert Ruiz has been transferred to the seven-day concussion injured list after a recent diagnosis spurred by continued headaches for the Nationals catcher.

Ruiz was watching from the dugout Monday night in San Diego when teammate Josh Bell hit a foul ball that whizzed past several players and then ricocheted back toward Ruiz, striking him on the right side of the head. Initial tests taken that night did not reveal a concussion, so he was placed on the 10-day IL with a head contusion.

Ruiz was still experiencing headaches in the days after the incident, though, so he was examined again by another doctor, who determined he had suffered what manager Davey Martinez referred to as a “mild” concussion.

The Nats made the transaction to move Ruiz to the 7-day concussion IL, which actually makes him eligible to return Tuesday when the team opens a homestand against the Tigers and Red Sox, three days earlier than he would have been eligible to come off the 10-day IL. He’ll still need to be cleared by a doctor before returning.

“If everything continues to go well, he’ll take that another test in seven days, and hopefully he’s OK to play,” Martinez said.

Ruiz did start taking some swings in the cage today, but there are more vigorous baseball tests he still needs to prove he can get through without issue before he can come back to play.

“He’s allowed to do anything he’s capable of doing,” Martinez said. “If he feels any symptoms, then he has to back off. He’s in there with the trainers. So far, he’s hit. The next big thing for him is going to be the running and bouncing around. He said that’s when he felt it the other day, just running and moving his head around.”

With Ruiz out, Riley Adams tonight makes his third straight start behind the plate. Drew Millas, who was promoted from Triple-A Rochester to take Ruiz’s roster spot, is likely to catch one game of this weekend’s series against the Angels.

* Derek Law experienced a setback following his most recent minor league rehab outing, with a return of the soreness in his forearm that originally hindered the veteran reliever back in the late stages of spring training.

Law pitched Wednesday in Rochester, bumped up to Triple-A after two appearances the previous week for Double-A Harrisburg. Facing a Syracuse Mets lineup that included players with big league experience including Mark Vientos and Francisco Alvarez, Law gave up three runs and four hits in one inning, with diminished velocity reported.

According to Martinez, the 34-year-old reported soreness the next day, so the Nationals decided to shut him down for the weekend. He’ll attempt to throw Tuesday, and if he has no lingering issues he could pitch again Wednesday.

“We got to this point,” Martinez said. “We can give him a couple days off and see if we can get him back to where he was a few days ago.”

Law ranked among the major league leaders in relief appearances (75) and innings pitched (90) last season. His absence has been felt by the Nationals, who enter play today with a 5.84 bullpen ERA, second-worst in the majors.

* Paul DeJong, attempting to return from several fractures suffered when he was struck in the face by a fastball in mid-April, will continue playing for Harrisburg this weekend. He’ll rejoin the Nats on Tuesday in D.C. and meet with team doctors and staff members to determine if he’s ready to come off the IL yet or not. The veteran infielder, who was the Nationals’ Opening Day third baseman but has since ceded that job to rookie Brady House, played second base for Harrisburg and said he was comfortable there, opening up the possibility he returns as a utilityman.