General manager Rick Hahn said in a statement that Robert informed the team's medical staff of the symptoms Monday night. The team is awaiting further test results.
"Our hope is that his symptoms resolve quickly and that the testing protocols clear him to return to the active roster soon," Hahn said.
The 23-year-old Robert is hitting .305 with one home run and six RBIs in 21 games. He finished second in the AL Rookie of the Year voting last season.
Chicago recalled right-handed pitcher Alex McRae and outfielder Luis Gonzalez from their Schaumburg, Ill., training facility.