Left-hander Chris Capuano was given the nod in Billingsley's place.
"He's gonna get an MRI this morning," manager Don Mattingly said before the Dodgers lost 7-2. "We should know something, depends on whether we can get somebody to read it or not on a Sunday, but we're hoping to know something by the end of the day.
"Apparently, he's been feeling something but he hasn't really told anybody. ... (Head athletic trainer Sue Falsone) said something to (Rick Honeycutt) that Bills had something to them during (Saturday's) game. ... He said it's been going on a little bit, but he looked at it as normal stuff."
Billingsley, 4-9 with a 4.30 ERA, wasn't at Dodger Stadium during media availability and wasn't available for comment.
Mattingly remained hopeful the MRI results would reveal nothing serious and Billingsley wouldn't miss many, if any, starts moving forward.
In fact, the pitcher tried to convince his manager to let him pitch.
"My only issue with it all, and we talked with Chad about it, is just not letting somebody know, so we can kind of be paying attention to it," Mattingly said. "Sue and those guys, they go to school for a long time and they're pretty smart. They can't really help you if you don't talk to them.
"It's really all our guys. We talk about it all the time. Guys in general just hold it in thinking they'll be fine. We all do it. So it's one of those issues we've gotta keep fighting."
Billingsley's absence highlights a mixed-and-matched lineup for the Dodgers Sunday afternoon. Center fielder Matt Kemp, two days back from his second stint on the disabled list, was given the day off, although Mattingly reassured the decision was pre-planned and purely precautionary. The All-Star outfielder was replaced by Tony Gwynn Jr.
"He wanted to fight me a little bit, but I told him I'd let him roll after this," said Mattingly of Kemp.
Andrew Kamenetzky is a reporter for ESPNLosAngeles.com.