Billingsley is 14 months removed from Tommy John surgery. The normal rehabilitation period for pitchers undergoing that surgery is 13 to 18 months.
He is scheduled to visit orthopedist Neal ElAttrache on Thursday. Billingsley had hoped to rejoin the Dodgers in early July, but now he and the team will await a diagnosis and revised timetable.
Billingsley, 29, made one rehabilitation start in April, but he experienced discomfort that was diagnosed as tendinitis and the tearing of scar tissue. He returned for a second rehabilitation start on Sunday, but he said he could not pitch at full strength during a bullpen session Tuesday. He did complete the session.
"He didn't feel like he could max it out," Dodgers Manager Don Mattingly said Wednesday.
"I'm sure he's frustrated. Hopefully, it's another minor thing."
The Dodgers selected Billingsley in the first round of the 2003 draft, one pick after the Angels took onetime phenom Brandon Wood, and promoted him to the majors in 2006. The Dodgers can pick up his 2015 option for $14 million or buy him out for $3 million.