Vaginal discomfort about a week before period

Hillary • we're all here for the same reason, "My vaginas normal right?!"
Hey ladies, I always have a bit of vaginal discomfort and itchiness about a week before my period..is this something anyone else experiences or something I should be concerned about? I've been checked for STI's 2 times since noticing this and both times I have been clear of any STI's. Any advice ladies??