Only bleed during sex

I'm getting a little nervous because my period started 3 days ago during sex with my fiance. Then I didn't bleed at all the next day. So we had sex again. Same thing happened I bled during sex but the whole next day nothing. We didn't have sex last night. I also didn't bleed and there is still no blood this morning. This past month had been really stressful for both of us. So I'm not sure if this is stress related or some other issue. Advice please!