On Sunday in Atlanta, it was a right hamstring cramp, but in Friday's 9-5, 12-inning loss to the Braves, Billingsley left after six innings with a strained left hamstring.
The injury occurred when Billingsley ran out of the batter's box after singling in the bottom of the sixth.
"[I was] running down the first-base line, and about halfway I felt a grab in my left hamstring," Billingsley said after the game. "No good thoughts were going through my mind at that time."
After the inning ended, Billingsley debated whether to alert the Dodgers' medical staff or head back to the mound and try to pitch through the seventh.
"I was thinking to myself, 'Should I say something now, or if I should go back out there and try to throw?'" Billingsley said.
"I went back out there and tried to throw one pitch and couldn't do it, so I just walked off the mound."
Manager Joe Torre said that Billingsley is going to get checked out Saturday morning, and the manager didn't know if the injury would affect Billingsley's next scheduled start on Wednesday in San Francisco.
"I wish I knew. We'll let you know tomorrow," Torre said. "Early signs are that it's not a full-blown thing."
Billingsley also said that the hamstring strain didn't look too serious, but he looked a little distraught about the state of his left leg.
"You never know," he said. "Some little things linger on a little bit."
David Ely is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.