Broxton appeared in two games for Triple-A Albuquerque last week as part of his rehab assignment, but was shut down this weekend after complaining of soreness. He had allowed one run and struck out five while pitching one inning in each appearance for the Isotopes.
Dodgers manager Don Mattingly didn't have results of the MRI before the team's game at Minnesota on Monday night.
"The fact that he had two outings, taken a lot of time off and slowly came back with two outings, and then had maybe a day and a half, two days later he's feeling the same pain," Mattingly said. "Obviously that's not a good thing, and it kind of shuts the rehab to a point where we've got to find out what's going on again."
Broxton was placed on the 15-day disabled list on May 6. An MRI showed a bone spur along with some bruising, although there was no structural damage.
The right-hander was 1-2 with a 5.68 ERA to begin the season, converting seven saves in eight chances.