OAKLAND -- It has been a week to forget for A’s pitchers.

Originally scheduled to throw a rehab outing on Tuesday, Sean Manaea instead has been shut down from throwing after feeling soreness on his right side. The tough news comes after the A’s lost top starter Frankie Montas to an 80-game suspension on Friday and closer Blake Treinen to the 10-day injured list with a rotator cuff strain on Saturday.

Manaea described the issue as “just a little tightness” and does not consider it to be serious, but the A’s do not have a specific timetable for when he might get back on a mound. He last threw 60 pitches in a simulated game at the team’s Minor League complex in Arizona on Thursday.

“He’s got a little bit of a side soreness, so we’re shutting him down for a little bit,” A’s manager Bob Melvin said Sunday. “I don’t know if it’s an oblique or if he’s just feeling it a little bit in his side. We’re cutting back on him for a little bit here to get healthy. It’s not the arm, which is good.”

Out since his September surgery to repair a torn labrum in his left shoulder, Manaea was targeting a return to the Majors just after the MLB All-Star break. It’s unclear at this point if this setback changes that estimation.

Schlitter arrives

The A’s recalled right-hander Brian Schlitter from Triple-A Las Vegas to take Treinen’s spot on the active roster.

In 27 games with Las Vegas, Schlitter went 4-1 with 10 saves and a 3.89 ERA. His 10 saves are tied for second in the Pacific Coast League.

“He’s got a good sinker and is pretty good on right-handers,” Melvin said. “He threw 40 pitches the other day, so he gives us some length. I don’t know that he has a set role; it will be more of a day-to-day proposition.”

If Schlitter does appear in a game for Oakland, it will be his first Major League game since June 14, 2015, with the Cubs.

“I just kept doing what I’ve been doing my whole life,” Schlitter said. “It’s reassuring and still means something that people are able to give me this opportunity to get back here.”