"He's going to get an MRI [Monday] just to see the structure in there and just to see if there's anything more than what they're finding," Sandberg said. "It seems to flare up and then go away fairly quickly. So, he's getting checked out [Monday]."
Brown came out of Friday's series opener with Chicago in the sixth inning and has pinch-hit twice since then.
He left Philadelphia's game against the D-backs on Aug. 24 with inflammation in the right Achilles, and returned to the lineup on Aug. 29 against the Mets before the most recent flareup on Friday.
Manny Randhawa is an associate reporter for MLB.com. Follow him on Twitter at @MannyBal9. This story was not subject to the approval of Major League Baseball or its clubs.