The NFL and the NFLPA are investigating the circumstances surrounding a concussion sustained by Pittsburgh Steelers quarterback Ben Roethlisberger during Sunday's game, sources told ESPN on Tuesday.

Meanwhile, Roethlisberger told 93.7 The Fan on Tuesday that he had more tests, does not have a concussion and should practice Wednesday and play Sunday. The Steelers, though, said their QB will remain in the protocol.

Although there's been agreement that Roethlisberger's acts of self-reporting his symptoms and taking himself out of the game are positive steps for concussion awareness, the independent spotter system put in place this season is supposed to keep players from having to do that.

As they did last week with St. Louis Rams quarterback Case Keenum, the league and the union are investigating why the spotter and the officials didn't stop play and/or use a medical timeout after the hit that caused Roethlisberger's concussion.

"It's great that he self-reported," a union official told ESPN, "but that's not the process we all signed up for."

Ben Roethlisberger passed for a season-high 456 yards Sunday but missed the final few minutes of Pittsburgh's loss to Seattle and later was placed in the concussion protocol. AP Photo/Ted S. Warren

On the fifth play of a 14-play scoring drive, Roethlisberger took a high-low hit from Seahawks pass-rushers Michael Bennett and Bruce Irvin, which resulted in a roughing-the-passer call. Roethlisberger was on the ground for a few seconds after the play. He got up with the help of teammates and didn't show noticeable symptoms while standing. He proceeded to play the next nine plays, which led the Steelers to the red zone for a field goal.

Roethlisberger said Tuesday he was immediately removed from the game by Steelers doctors after he told them that he was "having some vision problems" upon returning to the sideline. He said Tuesday that he still has a migraine.

Backup QB Landry Jones manned the offense on the Steelers' final drive, while Roethlisberger headed to the locker room.

The NFL added independent certified athletic trainers in 2011 with the intent to have them serve as spotters from the press box. A video component was added during the 2012 playoffs.

Starting this year, those spotters have been given the ability to buzz the officials for medical timeouts if a player appeared to need medical help. Those spotters' duties include an emphasis on head injuries and concussions but are meant to span all potential injuries.

The union also continues to monitor the Keenum situation. Sources told ESPN NFL Insider Adam Schefter on Sunday that the Rams won't face discipline for their handling of the concussion protocol in that case. The union, however, would like to know why not, especially if the investigation showed that the protocol breakdown in that case was the fault of the Rams' medical staff.

ESPN Staff Writer Jeremy Fowler contributed to this report.