Levy never fully recovered from the knee injury he suffered in the first game of the 2016 season. He underwent surgery to repair a torn meniscus and returned to play in the final five games of the season, including the playoffs.
Levy required another knee surgery in April in order to have cartilage removed and redo the meniscus repair.
The Lions released him in March. Levy said the team cleared him the day before cutting him, despite Levy saying three other doctors told him the knee was not healthy.
"I figured there was something wrong because they passed me on a physical when I couldn't even sit down to a chair or get into a linebacker stance at the time," Levy told ESPN. "In my mind, I didn't think about the legal contract part of it. I thought, this is f---ed up. I can't get into position; how can I pass a physical? I didn't know it was a physical the first time.
"I went in for just a follow-up for my knee, we go through the exam or whatever and I see he puts 'pass' on it for the physical. I'm like, 'OK, this ain't right.' So I called my agent and I'm just now learning about the process."
Levy said this occurred around a day before he was released by the club, at the start of the league year. Levy said he didn't yet have a date for the grievance hearing but that the grievance is filed and "it's in line to be processed."
Said Lions coach Jim Caldwell on Wednesday: "First of all, I didn't read it, so I don't know what's said. Secondly, grievances filed in this league, it's a player's prerogative. That's why they have the CBA. That's why they have an opportunity to litigate things of that nature and they happen all the time. But I'd rather talk about people that are here than aren't here."
Injury grievances are not uncommon filings in the NFL.
"We followed everything by the rules," Caldwell said. "We did exactly what we were supposed to do. That's probably all I have to say on that."
Levy, 30, spent most of his final two years with the Lions injured. He lost all but one full game to a hip injury in 2015.
He has been rehabbing in Florida, Wisconsin and Michigan since his second knee surgery. Levy said Tuesday he hasn't started running yet and wants to take his time to make sure everything is correct before he tries to play again.
Prior to the injuries, Levy was one of the top 4-3 linebackers in the NFL. He had a 151-tackle season in 2014 and a six-interception season in 2013.
"Just kind of, it's frustrating, man, because the way I was trending, I just hit a wall and it's like, I feel like it could have been avoided last year," Levy said. "I feel like it could have been avoided if I was shut down earlier.
"The cartilage is wearing because my knee was jacked up. Like the cartilage is pretty much gone now because I'm out there, and you're telling me I'm not going to make it worse, it's just a psychological injury. And now I'm here, maybe missing another season because of it. And it's frustrating, man. I was there for a decade and I never complained about any of my injuries.
"I've played through a ton of stuff that, the injury report probably tells half the story. I'm battling every day; I put in a lot of time, a lot of hours for nearly a decade and then you cut me and tell me I'm not hurt. And now I have to go through a legal process to prove that I was injured. It's insulting, man. It kind of left a sour taste in my mouth."
When he made the decision to return initially, he didn't think of the long-term effects of what might happen, even if he played the limited role that he did. Plus, he saw the excitement around the franchise and the chance to win a division for the first time since 1993.
"In the moment, they tell me I can't make it worse," Levy said. "The doctors are telling me that, the coaches are telling me that, like the doctor is saying I can't make it worse and now, I can. For my long-term health, yeah, I regret it. ... I was just trying to prove I could be out there and help the team win, and hopefully that would be some saving grace for next year, like I was still trying to battle it out for everybody.
"But now I'm stuck sidelined, struggling to get up and down stairs."
He added: "Struggling through 20 plays for four games isn't worth losing a year, maybe more."
Levy said he would still like to play if his hip, knee and back recover well from the injury and that five or six teams have reached out -- but he has to tell them the same thing: "I won't be cleared until November, December."
He's also going to be wary of any medical advice he would receive from inside an organization.
"I'd be foolish, at this point in my career," Levy said, "to put my health in the well-being of NFL doctors."