It wasn't drugs and it wasn't a tiff with Ashley Greene over Joe Jonas that pushed Disney star Demi Lovato into treatment. So, what was the reason? A physical altercation with one of her dancers, according to PEOPLE.

"As she did on most nights off, Demi invited her band, dancers and her parents to dinner," says a source close to the singer. "Afterward, she broke off with a very small group."

The next day, her stepfather and tour managers were worried about the group's conduct the night before. And according to a source close to the situation, Lovato and the group had been partying.

"When tour management found out about this, they talked to the people involved, including Demi," source said. "Demi reacted badly and perceived that someone on tour had told on her."

After the group was reprimanded, Lovato confronted a young dancer in her tour crew, suspecting that she was the one who told on the group. "There was a short, physical altercation," the source said.