"I think it's something on the bottom of my foot, maybe in the arch area," McCann said on Wednesday.
McCann said that he has been trying to manage the injury since last Sunday, when he had to leave a game against the Rangers at Yankee Stadium due to cramping in his right foot and calf.
"It just didn't go away," McCann said. "It just stayed in the bottom of my foot and crept up into my calf. That's why I had a hard time putting weight on it."
McCann has previously had X-rays on the foot, which were negative. He was replaced by John Ryan Murphy behind the plate for the bottom half of the frame.
"We've been managing it, and at times it's felt good, and at time it's hurt a little bit," Yankees manager Joe Girardi said. "Today, for whatever reason, it got really sore after that first inning so we had to make a move."
In the second year of a five-year, $85 million contract, McCann is batting .248 with eight home runs and 33 RBIs in 45 games this season.
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch, on Facebook and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.