By Zach Koons The third-year signal-caller suffered a significant head injury in last Thursday’s game against the Bengals. The Dolphins already ruled out quarterback Tua Tagovailoa from this Sunday’s upcoming game against the Jets, coach Mike McDaniel announced Monday. Tagovailoa, who suffered head and neck injuries in last Thursday’s game against the Bengals, remains in the concussion protocol. The third-year quarterback left the contest in Cincinnati on a stretcher after his head hit the ground on a sack by Bengals defensive tackle Josh Tupou. McDaniel said Monday he was “confident” Tagovail…