Vagina Discharge and smells really bad during sex

This has been going on for a while now but kinda scared to go getit checked out. i have this white stuff that comes out of my vagina everyday but it doesnt smell. the only time my vagina starts to smell is after sex or during. anyone know what this is? and also...i've been trying 2 get pregnant....me and my boyfriend tried 4 times. during my most fertile days. but still nothing, zip..not prego but back to the question i asked. what is the horrible fish like smell?