Ross took a foul ball off his mask on Wednesday in New York, and said he's had a headache, nausea and fatigue, and has been a little irritable since then.
"I was a little off a couple days ago -- I'm probably always a little off," Ross said. "It's hard to tell what's normal for me, to be honest."
The move was precautionary, and the Cubs selected the contract of catcher Taylor Teagarden from Triple-A Iowa.
"The main concern is getting another foul ball [off the head]," Ross said. "I had that happen a couple years ago, and it put me out two months."
Ross was on the disabled list in 2007 for a concussion he sustained in a collision, and again in 2013. He tried to rush back after the latter incident.
"I took a couple more foul balls [off my head], and they ended up sending me home to my house in Florida for two months," Ross said of the 2013 experience. "I definitely don't want to go through that again."
Ross, who is working with a company that's trying to improve the padding on facemasks to minimize concussions, won't be behind the plate for Jon Lester's start on Monday. It'll be the first time Miguel Montero will work with the lefty.
"I know 'Miggy' and Jon have been talking, and I know David will be helpful in talking to Miggy about it," Cubs manager Joe Maddon said. "I think it'll be fine, and it could be something that benefits us down the line in case something else happens. If you get to the playoffs and you want to do something differently, who knows?"
Teagarden, 31, has appeared in parts of the last seven seasons with the Rangers (2008-11), Orioles (2012-13) and the Mets (2014), batting .202 with 21 home runs and 68 RBIs over 172 games. He has avoided concussions so far.
"I've taken lots of foul balls and taken bad swings to the head, and I've been fortunate enough to not have any chronic symptoms related to that," Teagarden said. "It is a tough spot for catchers."