Vagina discharge smells like asparagus pee?

the smell started yesterday... my period is suppose to start monday or tuesday (im on the pill) ive been having the normal spotting discharge for the last couple days but yesterday i smelled like i was on my period and today it has had the strangest smell.. i finally figured out it smells like your urine does after you eat asparagus... only thing is i havnt????? whats wrong with me? has anyone else had this problem?