Can white gooey stuff that comes out the vagina mean your period is coming or that it's cleaning out your system?

Normal: White discharge is normal for the vagina and it is, as you say, a way that the vagina cleans itself. Discharge can be clear or cloudy, thick or thin. So long as it doesn't itch or smell fishy, it's likely normal. Discharge can change based on what you eat, or exercise, or condoms or lubrication, or hormones. Many things can affect discharge.