Shaun Marcum, who was examined in New York on Thursday, underwent an MRI that revealed inflamed nerves in his neck, the team announced.
Marcum was treated with "trigger-point injections" to attempt to calm the inflammation. He will return to Port St. Lucie, Fla., and be idle for at least 48 hours.
Marcum has not pitched in a game since March 16. So even if his neck and shoulder pain dissipated -- which is no guarantee -- it would take some time to get ready for a major league game.
Aaron Laffey is poised to be promoted from Triple-A Las Vegas on Sunday to take Marcum's rotation spot. Darin Gorski has been reassigned from Double-A Binghamton to Las Vegas to plug Laffey's rotation spot in the Pacific Coast League.