Brooke Mueller Says Hospitalization Was Not For Overdose

Brooke was in L.A. Friday evening ... when she told TMZ she has obtained medical records to prove drugs were not a factor when her assistant found her unresponsive at 11 AM and called 911.

We broke the story ... Brooke was rushed to a nearby hospital and discharged several hours later.

TMZ spoke to Brooke's assistant ... who tells us she's new on the job, freaked out when she couldn't get Brooke to wake up and mentioned Brooke's history of drug abuse when she was talking to the 911 operator. "I made a mistake," the assistant says ... adding, "I overreacted."

But TMZ has learned ... Brooke's friends and family members, including her mother, have been very worried about Brooke's drug use for the past couple of weeks.

Publicly, Brooke's mom has been an apologist for Brooke ... but privately, she's expressed deep concern.

Last night, Brooke told us she had been making jewelry nonstop for the past several days ... and was so exhausted, she simply passed out cold.