"Right now, I would say he's going to miss the Colorado series," Bochy said. "We're hopeful this will clear up enough so that he can play in Chicago [against the White Sox on Friday]."
With expanded rosters, the Giants don't need to place Parker on the disabled list.
Parker on Friday said the symptoms started earlier in that night's contest and got progressively worse. He left the game during the fifth inning.
Gorkys Hernandez becomes the team's everyday left fielder with Parker sidelined. Hernandez has had an offensive surge recently, hitting .312 over his last 58 games, though he went 0-for-3 with a strikeout in Saturday's 2-1, 10-inning win over St. Louis.
Parker missed 96 games earlier this season after fracturing his right clavicle. He returned from the disabled list on Aug. 3.
Jonathan Hawthorne is a reporter for MLB.com based in the Bay Area. This story was not subject to the approval of Major League Baseball or its clubs.