Brown stuff during sex

I’ve been having sex pretty regularly for about 2 years and I’ve never had a problem with this. Recently only when I have sex I get like a reddish brown discharge or whatever and it’s kind of making me nervous and grossing me and my partner out. It’s not time for me to get my period and I’ve been on the same birth control for 3 years and have never spotted. If anyone has any ideas let me know. 👍🏼