Disney star Demi Lovato has bailed on an international concert tour with the Jonas Brothers -- and has checked into a treatment center to seek help for "emotional and physical issues" ... TMZ has confirmed through the singer's rep.
In a statement to TMZ, the 18-year-old singer's rep says, "Demi Lovato left her tour early this weekend in order to seek medical treatment for emotional and physical issues she has dealt with for some time."
We're told Demi is not seeking treatment for drug use.
The statement continues, "Demi has decided to take personal responsibility for her actions and seek help. She is doing just that."
The rep concludes, "[Demi] regrets not being able to finish her tour, but is looking forward to getting back to work in the near future."
Sources close to Lovato tell us the singer was in a physical altercation with a female member of her tour recently ... which was a "catalyst" in her decision to seek professional help.