Johnny Manziel is tackled after running into the end zone. (Justin Tang/The Canadian Press via AP)

Johnny Manziel was placed in the Canadian Football League’s concussion protocol Wednesday, although it is unclear whether his symptoms were the consequence of a huge hit he took in the Montreal Alouettes’ loss Saturday or a side effect of medication he is taking for what he has said is bipolar disorder.

“On Tuesday morning, Johnny Manziel mentioned to our medical staff that he felt symptoms that could be associated with the prescribed medication he uses for a previously diagnosed medical condition,” the Alouettes said in a statement. “He then missed practice in order to have some bloodwork done.

“In view of the hit he received on Saturday and the potential mitigating side effects of his prescribed medication, the Alouettes medical staff has placed Manziel under the CFL concussion protocol for further observation and precautionary reasons. Manziel will be closely observed and assessed in the next few days.”

Manziel remained in the game after a hit at the goal line led to a fumble that a teammate recovered for a touchdown. “Ran into a brick wall,” Manziel said of the play after the game. “That defense was fast, that defense was big and aggressive. They hit hard, they’re quick. But like I told these guys, you’re not going to take me out like that.” In his second start since being traded to Montreal, he completed 16 of 26 passes for 168 yards and rushed for 36 yards, including the play that resulted in the touchdown. Coach Mike Sherman defended the decision to allow Manziel, whose style of play leads to big hits, to keep playing.

“I was right there when it happened,” Sherman said. “He came off the field, sat down. We were going to go for two [points] and then the doctor said he’s out. Then we decided to go for one. I went over to the bench. He was talking coherently. It didn’t look like there were any problems. The official came in right beside me. He said, ‘This is what I have to see.’ So he came over and looked at Johnny and he said, ‘Oh, he looks okay.’ So that was that. There was a spotter and our doctors were there, so I left.”

On the drive back from Ottawa, Sherman said that Manziel seemed fine; he attended quarterback meetings both Tuesday and Wednesday.

“If I knew there was anything wrong with Johnny. . . I would never put a player in harm’s way and neither would this organization,” Sherman said. “The doctors looked at him. The spotter looked at him. He recited the playbook to us, which is not an easy thing to do. So at the point, he was ready to go in.”

Manziel, who is trying to resurrect a football career that ended after the 2015 NFL season because of poor performances and off-the-field incidents, said in February that he is taking medication for bipolar disorder.

“Going back throughout the last couple years of my life, I was self-medicating with alcohol,” Manziel told “Good Morning America.” “That’s what I thought was making me happy and helping me get out of that depression to a point where I felt like I had some sense of happiness. But at the end of the day, you’re left staring at the ceiling by yourself and you’re back in that depression, back in that hole, that dark hole of sitting in a room by yourself, being super depressed, thinking about all the mistakes you’ve made in your life. Where did that get me? Where did that get me except out of the NFL? Where did that get me? Disgraced.”

In May, he was briefly hospitalized for what his spokeswoman told The Post was a “reaction to a change in his medication” for that disorder.

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