Braun said he could miss Monday's series opener against the Marlins in Miami.
"From the very beginning, I should have taken more time off and gotten it right," Braun said after the game. "But I just continued to try to fight through it, play through it. It's at the point where it doesn't feel very good."
Roenicke said he would talk to Brewers GM Doug Melvin about Braun's situation during the team's flight to Miami.
"We've got to figure out what to do there," Roenicke said. "We've got to start going in the right direction with him, and sometimes it's not. I'm hoping we don't have to [place him on the disabled list], but we start making gains and he says, 'Yeah, I feel really good today,' and then all of a sudden it's a bad day and a setback.
"We keep going with this back and forth. He's out there playing, hitting third for us, and I expect the Braun that I've seen for the last two years, and he's not the same. He's still getting hits, he's still helping us win games, but he's not that guy that can carry a team like I know he can."
Roenicke said he had a plan for Braun on the upcoming, three-city road trip, which includes a pair of off-days between stops.
"Every time I swing the bat I have the ability to make it worse," Braun said. "We've done all kinds of different things as far as trying to figure out padding in the glove or on the bat. Maybe we'll figure out something that works."
Braun, who has contributed at least 30 homers and 110 RBIs in Roenicke's first two full seasons as Brewers manager, entered Sunday hitting .305 with nine home runs and 36 RBIs, a pace for 24 homers and 94 RBIs. He has been adjusting his swing to compensate for pain in his thumb, and was homerless in his previous 64 plate appearances.
That Braun's power has been sapped was evident by the Brewers' first-inning strategy on Sunday. After Norichika Aoki took a walk from Phillies starter Jonathan Pettibone, Jean Segura popped out a bunt attempt and Aoki was caught trying to steal second base. Braun then struck out on a foul tip.
Adam McCalvy is a reporter for MLB.com. Read his blog, Brew Beat, and follow him on Twitter at @AdamMcCalvy. This story was not subject to the approval of Major League Baseball or its clubs.