Foles was injured in Sunday's 17-3 loss to Dallas. He completed 11-of-29 passes for 80 yards prior to the injury.
Rookie quarterback Matt Barkley was put into the game and completed 11-of-20 passes for 129 yards. He was also intercepted three times.
Foles was making his second start in place of Michael Vick, who has a hamstring injury.
Foles must go though the NFL's concussion protocol before returning to the field.
Kelly said the Eagles won't rush Vick back into action until he is fully recovered.
Barkley, Foles and Vick are the only three quarterbacks on the Philadelphia roster. Kelly said if Foles and Vick are unable to play, the team will have to sign another quarterback.