Manager Terry Francona would not say whether surgery was under consideration.
"I think what we need to do is allow this process to kind of play itself out," Francona said. "With the ballclub's help and urging, he's going to get another opinion and we're trying to align that right now. When we have information that's solid -- and when and where and all that -- we will give it to you guys. I think they're in the process of trying to do that right now."
Through 97 games this season, the 33-year-old Swisher is hiting .208 with eight home runs, 20 doubles, 42 RBIs, 36 walks, 111 strikeouts and an uncharacteristically low .278 on-base percentage. Over the previous 10 seasons in the Majors, Swisher turned in a .255/.358/.462 slash line with at least 20 homers in each of the past nine years.
Swisher -- signed to a four-year, $56 million contract prior to last season -- battled a left shoulder issue last season, when he hit .246 with 22 homers and 63 RBIs in 145 games. He has dealt with issues in both knees this year, but has tried to play through the discomfort.
Francona said the most important approach now is for Swisher to get to the bottom of the injury.
"It's hugely important," Francona said. "That's why I think, with the club's blessing, get another opinion and then put everybody's heads together and see how to progress moving forward. We'll have some information, hopefully, pretty soon."
Jordan Bastian is a reporter for MLB.com. Read his blog, Major League Bastian, and follow him on Twitter @MLBastian. This story was not subject to the approval of Major League Baseball or its clubs.