Troubled diva Whitney Houston has reportedly checked in to a rehab clinic in Arizona in a desperate bid to kick her alleged drug addiction. The singer is seeking help at the Sierra Tucson clinic in Tucson, Arizona, according to US news show Extra. The news comes just weeks after Houston's sister-in-law, TINA BROWN, went public with her fears for the singer. Brown, the sister of Houston's husband Bobby Brown, claimed the soul star was constantly high in an interview with US tabloid the National Enquirer. She said, "The truth needs to come out. Whitney won't stay off the drugs. It's every single day. It's so ugly. Everyone is so scared she's going to overdose." Brown also took pictures of her sister-in-law's sordid 'crack den,' which the Enquirer posted on the front page. Houston's representatives are refusing to comment on the latest rehab news.