Bleeding during pregnancy...11w3d

Lauren • Married to my best friend and mommy of Mason since September 16th 2015!
I have had absolutely no bleeding throughout my entire pregnancy but yesterday I had been experiencing very minor abdominal cramping...didn't think anything of it until I stood up and felt a huge gush of blood fill my pants. I ran to the bathroom and the blood filled the toilet. It was dark red and some bright red. I was sure I was miscarrying to I hysterically called my husband and her rushed me to the ER where the did and ultrasound and found the baby to look just fine. The let me see him on the creek and he was so active, heart rate was 174...I just don't know what to think but I'm still bleeding some now and just so worried. Has this happened to anyone else?