Zimmerman, an all-star in 2009, has already had a stint on the DL from April 27 to May 8 for the injury, missing 13 games.

“I’ve been hitting for a while here and I don’t miss fastballs like I’ve been missing fastballs,” he said after going 0 for 4 in Saturday’s 3-1 win over the Orioles. “It’s frustrating. . . . If things keep going the way they have been going, we’re going to have to do something.”

After finishing Saturday, Zimmerman’s average dropped to .218 in 55 games and his inflamed right shoulder joint, which he only recently admitted wasn’t 100 percent, continued to be an issue.

Zimmerman will receive treatment on his shoulder – massages, ultrasounds – to help. But if that doesn’t improve the injury, the 27-year-old may need the cortisone shot.

Zimmerman is hitting .218, with a slugging percentage of .305 and on-base percentage of .285 — all career-lows. His hitting and shoulder have been a cause of uneasiness for Manager Davey Johnson, who has stuck with Zimmerman as his No. 3 hitter, confident he would snap out of the slump given his track record.

After talking with hitting coach Rick Eckstein and others, and watching Zimmerman miss balls he normally hits, Johnson decided it was time to get Zimmerman some help.

“I’m that concerned,” Johnson said.

Zimmerman mentioned the possibility of “using the all-star break” to help his shoulder heal. If he gets a shot on Thursday, the latest date he could go on the 15-day DL and avoid missing games after the break, he would miss only 10 games.

The hurt shoulder, Zimmerman said, has been an issue at the plate.

“It’s not like I’m swinging at bad pitches,” he said. “I’m just missing pitches that I usually hit. It’d be different if I was striking out and swinging at sliders in the dirt and swinging at fastballs above my chest or whatever. But I’ve been working decent counts and getting decent pitches to hit, and I just foul them back or am a tick late.”

Zimmerman is an unusual position. For so long, he was at his best when the Nationals were at their worst during his eight-season career. It earned him a six-year, $100 contract extension in February. And despite his cold bat, the Nationals are in first-place in the National League East.

“Everyone plays until basically they break, which isn’t always the smartest thing, but that’s how we’ve been raised in this game,” he said. “But I haven’t really been helping the team lately, offensively. I feel like I’ve done some other things to help the team win. It’s just frustrating. Obviously we’re playing good. We have a good team. And I want really bad to be a part of that.”

Zimmerman’s injury history has been recent. He missed 60 games last season because of a torn abdominal muscle, which required surgery. He also missed 20 games in 2010, and nearly 60 in 2008 because of a shoulder injury.