The Lakers are 2-4 since Bryant returned. They entered Thursday's play at 12-13 and in 11th place in the Western Conference.
"It's tough when you get in a streak like that," center Pau Gasol said. "He was fighting through and getting through the process of getting back on the floor after tearing his Achilles, and now you get this fracture. It's very hard for me as a teammate, as his friend, to understand that that happened to him. But what can you do? He's tough enough. He'll get through it and be back and ready to play."
Many across the NBA felt for Bryant after news of his latest injury spread Thursday.
Said LeBron James on Twitter:
Added Chicago Bulls coach Tom Thibodeau: "It's unfortunate. You hate to see it. He's coming off the Achilles and he's such a great competitor. It's bad for the league -- but he'll bounce back. He's got a lot of toughness."
The Lakers signed Bryant to a two-year, $48.5 million contract extension last month, taking him into his 20th season with the team.
If Bryant does miss six weeks, the Lakers will have paid him about $14.8 million this season for games he didn't play (40 total). None of that money is insured; to begin insurance coverage a player must miss 41 consecutive games with the same injury.
The Lakers have used 10 starting lineups, fifth-most in the NBA according to ESPN Stats & Information.
Steve Blake tore the ulnar collateral ligament in his right elbow earlier this month and is out at least another five weeks. Jordan Farmar has been out since Dec. 1 after tearing his left hamstring and isn't expected back for at least another week.
D'Antoni said Thursday that Xavier Henry will play point guard for the time being.
Nash, meanwhile, hasn't played since Nov. 10. He said Thursday that he felt "pretty close to 100 percent" after practicing for three days earlier this month but that feeling dissipated quickly.
The 39-year-old veteran said the goal now is to "take a step back, take a longer sample and try to prove to myself that my back can sustain the game of basketball."
"I just want to play, that's what gets me through every day," he said. "I want to play, I still love to play, and I still feel like I have the skills to do it. I'd like to finish my career on a positive note. I'm just fighting every day to get that little bit of joy from playing basketball and being one of the guys, running up and down the court and trying to beat somebody. That's what keeps me going every day."
Information from ESPN's Darren Rovell, ESPNChicago.com's Nick Friedell and The Associated Press was used in this report.