A night of partying may have been the cause of Demi Lovato's recent downward spiral, according to People.

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

After it was discovered that the small group had been partying, Demi was confronted. The source adds, "When tour management found out about this, they talked to the people involved, including Demi. Demi reacted badly and perceived that someone on tour had told on her."

The 18-year-old Disney star then reportedly confronted the dancer from the Jonas Brothers tour whom she thought was the tattle tail and "there was a short, physical altercation."

"Afterwards, Demi felt awful about her behavior and realized she needed to take personal responsibility for it. Because of this, and because of the battles Demi has fought throughout her life, both she and her family realized she needed to take steps to get help immediately," the source reveals to the mag.

Contrary to what some reports claim, Lovato "is not in drug rehab," clarifies the source.

As for whether Twilight star and Joe Jonas' girfriend, Ashley Greene, was involved in any way, Greene's rep released the following statement, "There was never an issue between Ashley and Demi, and there is no truth to any rumors about a conflict."