The Brewers made the move before Thursday's game against the Arizona Diamondbacks.
Hawkins is 0-3 with an 8.44 ERA. He was on the DL for 2½ months earlier this season with the same trouble.
Hawkins will have an MRI exam next week to determine the extent of the problem.
The Brewers selected the contract of right-handed pitcher Mike McClendon from Triple-A Nashville.
Milwaukee also transferred catcher Gregg Zaun to the 60-day DL to make room on the roster. Zaun was already lost for the season after surgery on his right shoulder.