Miscarried and didn’t know I was Pregnant... HELP!!

Yesterday me and my boyfriend were having sex but he hit something in there and it hurt SUPER bad, so we decided to do other stuff instead. When we were done with that we’re going to try again, but I look down and my comforter is COVERED in blood. I immediately jump up and grab tissues and run to the bathroom. My boyfriend took my sheets off and threw them in the wash, and ran a shower for me. As i’m sitting on the toilet, a blob just falls out of me. It looked like a huge blood clot. I started freaking out because 1. I knew it was probably a miscarriage but 2. I didn’t even know I was pregnant. I jumped in the shower and clots just continued falling out of me and I have not bled since except pinkish stuff when I pee. I have had slight cramps and pain in my vagina and back. Although i’m not ready for a baby, I still am very confused on what to do next. I was supposed to start my period the day it happened but obviously didn’t... so when will I have my period again? Just a BTW, I went to the ER last thursday and they took urine and blood... wouldn’t pregnancy have shown up? Also I had my period last month so am I sure this is even a miscarriage? What do I do next? Could I still have a chance of being pregnant (obviously not from the miscarriage yesterday) but still!!! Someone please help me out because I have lots of questions and have no idea what to think!