Brooke Mueller BACK IN REHAB

5/31/2012 8:40 PM PDT

Brooke Mueller -- BACK IN REHAB

Breaking News

Charlie Sheen
's ex-wife Brooke Mueller has once again checked herself into rehab for substance abuse -- sources close to Brooke tell TMZ.

According to sources, Brooke entered the undisclosed in-patient treatment facility a few weeks ago, following a puzzling visit to Charlie.

A source close to Charlie tells TMZ, Brooke recently came to his L.A. home and seemed out of it -- so much so Charlie felt she needed to be checked out by an addiction specialist.

We're told Brooke left before Charlie had a chance to get her examined by a professional. Brooke then decided to seek out substance abuse treatment on her own -- it's unclear why.

Brooke previously entered rehab earlier this year following her December cocaine arrest in Aspen.

Brooke is currently on probation from that case -- and as part of her plea deal, she's required to submit to random urine tests. A dirty test could put her in jail.