A lot of blood...

My boyfriend and I were having sex ( I was 18 weeks) and I started pouring blood. So much so, it was all over him, all over me, running down my legs and when I stood up I cupped my hands and ran to the bath room to see what was going on, it had pooled in my hand! It had chunks of what looked like skin in it. We rushed to the hospital where they checked everything. Ultrasound came back clear. Blood work said my levels were over 32,000 (normal range for second trimester) All aspects of the baby, placenta, uterus and cervix were fine. An internal exam showed no cuts or damage but the blood was for sure coming from inside my cervix (which was completely closed and posterior) I am now 21 weeks and everything is fine. Now I’m terrified every time we have sex! Has anyone had any experience like this? Why does this just happen with no reasonable explanation? Doctors can’t give me any answers so now I’m looking for experience answers and results ❤️