"I really don't know what's the whole problem. Everybody keeps saying it's a sprain or maybe a little tear there," Thomas said. "I don't know for sure if that's true. I'm hearing so many different stories. I don't know what to believe."
Thomas, the Saints' leading rusher in 2009, accounted for 280 total yards from scrimmage and one rushing touchdown in the first three games of this season. His injury occurred while he was being tackled late in the fourth quarter of a Week 3 overtime loss to the Atlanta Falcons. Thomas returned for the extra period in that game and gained 23 yards on a screen.
Thomas even returned to practice on a limited basis three days before New Orleans' Week 4 loss at Arizona.
"They were limited, but they got work today, and both of them are progressing quickly," Payton said then, adding that the players would be game-time decisions that week.
Thomas hasn't practiced since, though he seemed to be making progress Wednesday when he was present for the portion of practice open to reporters, participated in the team stretch and did some light jogging.
During the open portion of practice Thursday, however, Thomas was nowhere to be seen.
"All I'm thinking about is just trying to get healthy, just trying to get better," Thomas said. "I was told to stay off my foot. So that's why I'm in the crutches and in the boot. They told me to take a little pressure off, be on crutches for a little while just see how it does."
Thomas said he hasn't been given a timetable on his return, but he doesn't fault the doctors and trainers who have diagnosed and treated the injury.
"I'm not upset with anybody -- no person. I'm upset with my injury," Thomas said. "It's taking too long."
Fellow running back Reggie Bush also didn't practice Thursday as he continues to recover from a broken bone in his lower right leg. It's highly unlikely that Bush will return this week, a league source told NFL Network insider Jason La Canfora on Wednesday.
"Both with him and Pierre, there's a little bit of wait and see," Payton said Thursday. "They'd have to do something more than what we've seen these first two days (of practice this week). In Pierre's case, we put him in a walking boot to take some of the pressure off after his workouts leading up to this week, trying to rest it. So it will be unlikely that he gets to practice, and then with Reggie, we'll just monitor him again. We'll list the game status (Friday)."
Greer was injured during the Saints' Week 6 victory at Tampa Bay. Porter had arthroscopic surgery to repair his left lateral meniscus after injuring himself in Week 4. Shanle has missed two games since pulling his left hamstring.
Porter said he felt "pretty good," but he wasn't yet sure if he'd play Sunday.
"I'd like to," Porter said. "But I want to be smart, just as my coaches and my trainers want to be smart with me as well. If they don't feel it's the right time, they're going to hold me out. But if they tell me I can go, I'm definitely going to be happy and excited about that."
The Associated Press contributed to this report.