Los Angeles Angels All-Star outfielder Mike Trout is dealing with a rare condition in his back, making a timetable for his return to the lineup unclear, Angels trainer Mike Frostad said Wednesday, according to The Athletic's Sam Blum.

Trout, who's dealing with a condition called costovertebral dysfunction at T5, has been on the injured list since July 18 with back spasms.

"This is a pretty rare condition that he has right now in his back," Frostad said. "The doctor (Robert Watkins), who is one of the most well-known spine surgeons in the country, if not the world, doesn't see a lot of these."

However, the three-time AL MVP brushed off concerns when he spoke to the media Wednesday.

"I appreciate all the prayer requests but my career ain't over," Trout said, according to Jeff Fletcher of the Orange County Register. "I'm not worried about it. It's one of those things. You play and swing a lot and things pop up. I was playing through it for a while and it was one of those things where it was time to figure it out. We figured it out, and it's going in the right direction."

The 30-year-old added that he believes he will play again this season.

Trout has rib-cage inflammation that is causing the back pain, and Frostad admits there's some worry that the condition could sideline Trout long term.

"I think we have to have some concern on that," Frostad said, according to Blum. "… He's a little more upbeat today. And I think he's starting to feel like he's getting the benefits."

Trout recently received a cortisone shot that could take two weeks to work. He has not begun baseball activities, but he has started a core-stability program and cardio work, Blum reports.

Frostad also acknowledged that Trout will likely have to manage the condition for however long he continues to play.

"But long term, we do have to look at this as something that he has to manage, not just through the rest of this season, but also through the rest of his career probably."

Despite the Angels' slide down the standings, Frostad wasn't willing to make any proclamations when asked if Trout might be done for the campaign.

"We hope not. I don't think we're at that point where we're going to make that decision."