Jessica Campbell -- the former actress best known for her role as Tammy Metzler in "Election" -- died suddenly and unexpectedly last month ... according to her family.
Jessica passed away on December 29 in Portland, and though a full autopsy has been conducted by the Multnomah County Medical Examiner ... her family is still awaiting the results.
Her cousin, Sarah Wessling tells TMZ ... the day she died, Jessica worked a normal day seeing patients at her practice -- she was a naturopathic physician -- and returned home to visit with her mother and aunt.
Sarah says Jessica went to the bathroom but never came out, and when her aunt went to check on her ... she found her collapsed on the floor. We're told the aunt tried to revive her but couldn't, and neither could EMTs when they arrived.
The family says Jessica had been complaining of congestion and felt like she was getting a cold, but they didn't think it was COVID. The autopsy results are expected soon.