Dolphins quarterback Tua Tagovailoa diagnosed with concussion, flies back to Miami after being released from hospital

Miami Dolphins quarterback Tua Tagovailoa underwent additional testing Friday and remained in the concussion protocol a day after hitting his head against the turf during a game, a frightening moment that has sparked controversy about how the league handles potential head injuries.

Tagovailoa had a headache Thursday night and Friday morning, Dolphins coach Mike McDaniel said. The team was waiting still for results from the MRI, which McDaniel said was done out of "extra precaution" on top of the CT scans and X-rays taken the night before.

McDaniel said he had no timetable on when Tagovailoa might be able to return.