"He didn't feel great today," Johnson said. "(Trainer) Tim (Walsh) is gonna send him over to our doctors to get him checked out. He said he feels worse."
Humphries' status for Tuesday afternoon's game against the Boston Celtics is unknown. Johnson said he would provide an update before the game.
Humphries, 27, was a DNP for the first time this season on Sunday and has fallen out of Johnson's rotation. Gerald Wallace moved over to power forward and Keith Bogans was inserted into the starting lineup at small forward in place of Humphries.
Humphries, who signed a two-year, $24 million contract in the offseason, is shooting just 38.3 percent from the floor in December. He has started 20 of the 25 games he's appeared in this season, and averaged 7.1 points and 7.4 rebounds.
Mike Mazzeo covers the Nets for ESPNNewYork.com.