Witness Karen Faye also recalled how Jackson's reliance on medications coincided with the first time he was accused of child molestation in the early 1990s.
"Michael had to go on stage every night knowing that the whole world thought he was a pedophile," Faye said, shaking her head and crying.
Despite being asked by tour promoters, Faye said she refused to give the performer injections for pain.
She said Paul Gongaware, a promoter who later became a top executive with AEG Live LLC, then brought in doctors who treated Jackson in 1993 on his "Dangerous" tour, which she told jurors had to be halted early due to the singer's prescription drug addiction.
Faye testified in a negligent hiring lawsuit filed by Jackson's mother, Katherine, who claims AEG failed to investigate a doctor who cared for the pop star and was later convicted of causing his death in June 2009.
AEG denies hiring the doctor and says Jackson concealed his addiction to propofol, a powerful anesthetic that killed the singer.
Faye said she never witnessed the singer's treatments, but he appeared to become more dependent on prescription drugs in the years following the "Dangerous" tour.
She said she worried every time she saw a doctor arrive to treat Jackson.
"I was always worried that Michael was in pain," Faye said under questioning by Brian Panish, an attorney for Jackson's mother.
She said Jackson had a low pain tolerance except while performing.
She recalled that he complained more about back pain after he fell several stories from on on-stage bridge during a Munich concert in 1999. Despite the fall, Jackson finished the show.
His high-energy performances, however, led to sleepless nights afterward, she said.
Jackson's condition worsened during the singer's 2005 trial on child molestation charges, Faye said.
Although he was acquitted, the pressure of the case and media attention took its toll, she told jurors.
"He couldn't eat," she said. "He was afraid. He was in pain. He got thinner. His physical pain, his back pain, it all kicked in."
Faye spent about 90 minutes testifying about her close relationship with Jackson, who hosted her wedding at his Neverland Ranch and enlisted her to travel around the world with him.
She breezily described Jackson's meetings with Princess Diana and other dignitaries, his Super Bowl performance, and other larger-than-life moments from the singer's life. Jurors and spectators laughed at times as a parade of photos and videos shot during Jackson's performances were played.
"I was from Pittsburgh, Pennsylvania. I was just very normal," she told jurors. "I found myself working with this magical person."
She said Jackson was like a brother to her and enlisted her for another tour even after she gave birth to her daughter.
"I said, 'I can't go all around the world with you. I'm a mother now,'" Faye recalled.
"Michael never took no for an answer. 'Yes you can, it'll be great for her,'" she recalled him saying.
Anthony McCartney can be reached at http://twitter.com/mccartneyAP