Steve Kerr, the Golden State Warriors’ head coach, ruled himself out of coaching in Game 4 of its first-round series with the Portland Trail Blazers and on Sunday said his absence — due to ongoing symptoms from complications from a back surgery in 2015 — could potentially extend through the rest of the postseason.

Kerr said his symptoms worsened several days ago, and that he’s felt worse as the week went on. And after missing shoot around Saturday morning before Game 3, he decided he wasn’t in good enough shape to take the floor with his team for the game Saturday night, one Golden State recovered from a double-digit second-half deficit to win.

“You guys saw me at the end of Game 2,” Kerr told reporters during a news conference at the team’s hotel in Portland on Sunday afternoon. “I was very uncomfortable. I was uncomfortable at practice the other day.

“With things getting worse, I decided I couldn’t coach. So, as of now, I’m consulting with my doctors, hoping for some improvement. And, if I get improvement, I’ll get back on the sidelines. But I’m not going to that until I know I can help the team.”

What Kerr made clear, however, is that he did not believe a quick return and then having to go away again would help his team. Kerr told reporters he was hopeful he would return sometime within the next week or so and remain on the sideline for the remainder of the postseason, but said he wouldn’t hesitate to remain away from the team for the remainder of the playoffs if the symptoms did not abate.

“I’m not going to do that to our team and our staff,” he said. “We’re hoping over the next week or two — whatever it is — I can sort of make a definitive realization or deduction, or just feel that I’m going to do it or not.”

Last season, serious back problems sidelined Kerr for 43 games. Details of the issues he dealt with then were harrowing, involving leaking spinal fluid and debilitating headaches. Kerr had undergone offseason surgery to repair a ruptured disk, but complications forced him to have another procedure and take a leave of absence at the beginning of the season.

“I can tell you if you’re listening out there, stay away from back surgery,” Kerr said. “I can say that from the bottom of my heart. Rehab, rehab, rehab. Don’t let anyone get in there.”

When Kerr sat out last season, assistant Luke Walton took over head coaching duties and went 39-4 as the Warriors won their first 24 games en route to picking up an NBA regular season record 73 victories. But after Walton left the team at the end of last season to become the head coach of the Los Angeles Lakers, the Warriors made it a priority to replace Walton with a coach with head coaching experience in case there was a need for someone to fill in for Kerr this year.

That’s how the Warriors wound up hiring Mike Brown, who coached in Kerr’s place Saturday night. Brown has spent parts of eight seasons a head coach in the NBA, including five with LeBron James in Cleveland and parts of two with Kobe Bryant in Los Angeles. He’s won 347 games and made the playoffs six times, including reaching the NBA Finals with the Cavaliers in 2007 — the kind of experience the Warriors wanted to have at the ready in case Kerr couldn’t be available, like he wasn’t Saturday and won’t be again Monday.

“Mike is fantastic,” Kerr said. “I was on the couch in my room saying ‘We should put so and so in right now,’ and that guy was going to the table. Mike and I are thinking along the same lines … the whole staff is. We’ve gotten to know each other so well.”

Saturday was the first time Kerr missed a game this season. But now Kerr will miss the rest of this series and, barring a stunning Golden State collapse from up 3-0 on Portland, will possibly miss the beginning of the team’s second-round series against either the Los Angeles Clippers or Utah Jazz.

In the meantime, the Warriors — who, led by Stephen Curry, gave Kerr a game ball from Game 3 — will try to stay on course without him for however long he’s away from the team.

“‎Our coach is going through a lot right now, physically,” Curry told ESPN after Saturday’s game. “He told us this morning this is a situation where we need to rally and go out and win a game for him. But we felt that the way the game had gone, we had to fight and do it for him … and the way that he said it was that we had to win one for the Gipper. So, shout out to Coach Kerr.”

The question now is how much longer Curry will have to be shouting out Kerr in postgame interviews, rather than speaking to him on the sidelines during games. Judging by his comments Sunday, it could be awhile.

Cindy Boren contributed to this report.