"I was stained with a role"
I think it means she was given (or gave herself) a role to play in her life
"In a day not my own"
This role was not what was right for her, and so it was like she was "stained". It was not her "day", because she hadn't taken contol of her life and what she really wanted, and didn't really acknowledge or know who she really was (ie. what her true "role" was)
Just my interpretation