Matz was experiencing soreness in his left forearm and returned to New York on Sunday to undergo a battery of tests.
"He's been able to pitch fine and swing the bat fine, but at this point, when it was bothering him today, we figured we better go get it checked out," Mets manager Mickey Callaway said.
Matz felt intermittent soreness for the better part of two weeks, Callaway said, and last started a game Friday in Milwaukee.
Matz owns a 3.86 ERA and 3-2 record in seven starts this season. In five seasons with the Mets, he is 23-28 with a 3.97 ERA.
--Field Level Media