A Reds spokesman said Bailey would be examined by team physician Dr. Timothy Kremchek in Cincinnati on Monday.
"We don't think it's anything serious," Bailey said. "At the end of the second and beginning of the third, I couldn't quite get loose. I wanted to stay in the game, but they weren't going to let that happen.
"It wasn't agonizing pain or anything like that. It could be something minor. There wasn't one pitch where I felt something. It kind of slowly crept up."
Reds manager Dusty Baker and trainer Paul Lessard went out to check on Bailey. After a lengthy discussion, Bailey -- Cincinnati's first-round draft pick in 2004 -- walked to the dugout and was replaced by Micah Owings.
Bailey allowed three runs and four hits over 2 1/3 innings. He threw 46 pitches.
On May 12, Bailey threw his first career complete game, a four-hit, 5-0 win at Pittsburgh in which 73 of his 90 pitches were strikes. In his next start Tuesday, he worked seven innings and got a no decision against the Milwaukee Brewers.
It was the second straight day the Reds' rotation was hit by an injury. On Saturday night, Johnny Cueto left after six innings with a blistered finger on his right hand.
Information from The Associated Press was used in this report.