Reserve goalkeeper Matt Nyman has been diagnosed with a subdural hematoma, head athletic trainer Holly Garlick said.
A subdural hematoma is a pocket of blood between the brain and the skull.
Nyman, 24, began complaining of headaches after diving during warmups before the June 23 game against D.C. United. Nyman does not need surgery, but he is prohibited from physical activity for three months.
NEW ENGLAND: The Revolution signed former Portuguese first division player Tony Frias III, 21.