sex causing period???

Grace • I'm chillen 👸🏼
I finished my period on Friday and then the next day I was having sex with my boyfriend and towards the end he's like "grace you're bleeding" and it didn't LOOK like period blood but idk I've been bleeding since, do you think it could've caused my period to start again?? And then on <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> it won't let me say that my cycle started again 😭 what do you think??