Sensitive topic... possibly

So Ive been on nexaplanon for almost 2 years and I still have had “pregnancy scares” well atleast I thought I did. Every time I got my hopes up it always turned out I wasn’t. My period has became very regular always on the 13th. I didn’t have it this month and Hester me and my boyfriend had sex about 15 minutes later I got up to go shower and A LOT of blood started running down my legs. I wasn’t bleeding before hand and I’ve had some pain like where my ovaries or uterus area is. Any ideas