Bears linebacker Hunter Hillenmeyer is feeling fine, just three days after the club ended his 2010 season.
But asked if he could have returned this season, Hillenmeyer said, "I don't know.
"One of the hardest things about a concussion is you don't really know."
Hillenmeyer suffered a concussion in the third preseason game, skipped the preseason finale then was cleared to play in the season opener last Sunday against the Detroit Lions. But Hillenmeyer complained of dizziness in the first half.
"I wouldn't have played in the first game if I didn't think I was better and when I got checked out at halftime of the game, the doctors say there's no way to know for sure if it's a lingering effect of a concussion," Hillenmeyer said. "It could be from allergies. There's a hundred things that could cause dizziness."
Hillenmeyer wouldn't pinpoint the number of concussions he's had (there was a documented one in 2006), only saying, "I've had several," but he could understand the team's concerns based on his history.
"As hard as it was to end up on IR after playing one half of one game, I respect their decision to err on the side of caution," he said.
So will he retire?
"I'm certainly not ready to say that, at this point," he said. "I know I'm obviously done for the year so that gives me at a minimum eight or nine months before I'm doing football-related activities again. That's certainly enough time to evaluate and make those decisions down the road."
Even then, though, Hillenmeyer likely won't have any testing to factor into his decision-making.
"I know I'll feel OK then," Hillenmeyer said when asked what may change in eight or nine months. "I already feel pretty good. It wouldn't be as long as I felt normal I would play.
"It's more having time to digest it and reflect and figure out what's in me and my family's best interest."
The team's NFLPA player representative, Hillenmeyer will continue to fulfill his duties in what is a critical year for players and owners since there's no collective bargaining agreement beyond this season.
Hillenmeyer added that he didn't believe his NFLPA duties influenced the team's decision.
"But from the conversations I had with Lovie [Smith] and with Jerry [Angelo], I obviously can't prove that but I would be shocked," Hillenmeyer said. "I certainly know Lovie well enough to know that wouldn't have played any role.
"He didn't want to be part of a decision forcing me back on the field in a situation where I could do damage to myself."
Hillenmeyer acknowledged that dealing with concussions is a "tricky issue." He said he was tormented about telling team doctors about his symptoms against the Lions.
"And if I'm fighting that battle in my head, you know there's guys with much less secure roster spot and aren't vested veterans who don't have to worry about the financial part of the situation who might even know and not care," he said.
Hillenmeyer proposed something similar to Major League Baseball, which has disabled lists that allow players to return after a certain time period.
"The situation's never going to be perfect but anything they can do like that, whether it's adding people to the roster or finding something where it's not an all-or-nothing, IR-and-you're-done situation," he said.
But he feels "lucky."
Hillenmeyer said he's talked to other players who suffer a concussion then complain of symptoms months later.
"I've never had anything like that," he said. "In that respect, I feel like I'm one of the lucky ones that have managed things correctly."
Hillenmeyer, 29, is coming off his best season in the NFL. He was second on the team with 105 tackles, and he filled in admirably for Brian Urlacher. He has degrees from Northwestern and Vanderbilt, but Hillenmeyer said it's difficult to think about his long-term future.
"If you don't put safety as the top priority, it's hard for a guy my age -- and at 29 I'm one of the older guys in the league -- to think about how this is going to affect me when I'm 50 or 60," he said. "I don't think that's a rational factor, especially when you're talking about a 23-year-old who had never earned a real paycheck. There are certainly a lot of factors that come to play. As far as how I weigh those on an individual basis, that's none of anybody's business."