SAN DIEGO — Chad Bettis hit a wall in Saturday’s sixth inning — and on Sunday, it became apparent why.

The Rockies moved the right-handed starter to the 15-day disabled list with elbow inflammation in his pitching arm.

The move allowed the Rockies to keep a nine-man bullpen while also adding starter Eddie Butler to pitch against the Padres on Sunday afternoon.

“We’re going to be real conservative with this one,” Rockies manager Walt Weiss said.

In 13 starts since he was called up from Triple-A in May, Bettis is 5-4 with a 4.88 ERA. The 26-year-old was producing like the Rockies’ second-best pitcher behind Jorge De La Rosa. But in his last six starts, Bettis is 3-2 with a 6.40 ERA.

On Saturday, Bettis held the Padres to two hits through five innings. And he worked through two quick outs in the sixth.

But then he walked two batters, gave up a two-run double to Matt Kemp and walked another.

Bettis after the game said he felt arm fatigue in the sixth.

“I got a little tired. I couldn’t find the strike zone after we got two outs,” he said.

The Rockies earlier this season lost closer Adam Ottavino to Tommy John surgery after what seemed like a triceps injury turned out to be an elbow ligament tear. They also have Tyler Chatwood still recovering from Tommy John surgery last year.

With Bettis, the Rockies are playing cautious.

“It’s always a concern when we talk about the elbow,” Weiss said. “But it’s real preliminary right now. We felt like either way he’s going to need a little bit of a breather here. So right now we’re calling it elbow inflammation.”

With Butler now part of the rotation, the Rockies have just four healthy starters. David Hale remains out with a strained groin. But Colorado has a scheduled off-day Thursday and won’t need a fifth starter until July 28.

Nick Groke: ngroke@denverpost.com or twitter.com/nickgroke