Nash will be re-evaluated Monday and was held out of the final portion of the game "as a precaution," according to the team. The Bulls won, 92-86.
Nash received contact to his left leg from Chicago's Kirk Hinrich as he turned the ball over with 9:18 remaining in the third quarter. The contact was near the same spot where he suffered a fracture in the leg last season. He stayed in the game until there was 5:00 remaining in the quarter and went straight to the locker room.
"I just took a knee to the spot where I broke my leg," Nash said. "Ever since I did that I've had a lot of nerve issues there and it just really flared up on me. I don't think it's going to be a long-term thing at all. Hopefully it's something that can just settle down this week, hopefully by Tuesday."
The Lakers host the Utah Jazz on Tuesday.
"[Once] that nerve flared up and I started to compensate, I wasn't going to be very effective ... and I also was going to risk going back on all that work I did to get back on the court," Nash said.
Lakers coach Mike D'Antoni said Nash's back started to tighten up from the nerve issues, causing the veteran point guard to limp on the court.
Nash, who turned 40 on Friday, had played in three of the Lakers' last four games after missing nearly three months of game action because of nerve root irritation in his back and hamstrings. Nash finished with eight points on 3 for 4 shooting, two assists and two rebounds in 22 minutes against the Bulls after averaging 13 points and 7.0 assists in his first two games back against Minnesota and Philadelphia.
Nash said he had a "gut feeling" that it would not be a serious setback and was in good enough spirits after the game to meet with Los Angeles Clippers assistant Alvin Gentry, who was at Staples Center for the Clippers' game against the Philadelphia 76ers later Sunday evening.
Gentry coached Nash in Phoenix.
"It wasn't like I broke it again," Nash said. "I just kind of irritated the nerve and I'm hopeful that all the stuff that I've been doing will be able to overcome that little bit of irritation. It's kind of transient and hopefully I'll wake up tomorrow and feel better."