Ben Affleck's Ex-Nanny Files Restraining Order Against 'Erratic' Acquaintance

Ben Affleck's ex-nanny has filed a restraining order against an alleged admirer she says took things too far ... claiming he's continued to try and contact her even though she asked him to stop -- and she even suspects he gave her cocaine instead of Adderall.

Christine Ouzounian -- Affleck's nanny while he was still married to Jennifer Garner -- filed legal docs asking for a temporary restraining order against Matthew Humiston ... claiming he acted erratically at a work conference last month, grabbing her wrist so hard that it was sore for days after.

Ouzounian says she blocked Humiston ... demanding Matthew not reach out to her again. She says this alleged incident was just the latest in a series of problematic interactions she had with him dating back to December.

During this time, Christine claims Matthew gave her cocaine instead of her Adderall -- which she uses for medical purposes -- and regularly made derogatory statements to her ... before changing his tune and asking her to marry him.

Christine says she's worried Matthew could ruin her professional reputation ... and, she's included what she says are numerous communication attempts by Matthew since she cut off contact with him -- alleging he's called, texted and emailed her repeatedly.

You may remember Ouzounian ... who reportedly told her friends she had an affair with Affleck while he was married to Garner -- though he's always denied the claims.