What Is The White And Excessive Discharge During Periods?

Hi, I have a question about excessive discharge during intercourse. I have this discharge every time my partner and I are intimate. I have it normally as well, but during intercourse the amount increases. it's milky in consistency and somewhat sticky. I have no pain whatsoever. It doesn't smell foul or fishy, but it reminds me of something metallic (like...iron?) Can you tell me what this is?