Fernandez is "almost certain" to head the disabled list, and there is no timetable for his return, according to The Miami Herald's Clark Spencer.
Fernandez threw only five innings in his last start, his shortest outing of the year. Two starts ago, he threw 112 pitches, his most since coming back from injury.
Fernandez missed most of last season after undergoing Tommy John surgery in May 2014. He returned to the mound on July 2, and is 4-0 in 2015 with a 2.30 ERA and 53 strikeouts in seven starts.
In his career, Fernandez is 20-8 with a 2.26 ERA and 310 strikeouts.