placenta separated from the uterus

I'm freaking out!!!!  I'm 6w 6d pregnant with my first baby and had an awful scare this week.   While I was at work I felt wetness as if I was getting my period.  By the time I got to the bathroom I was gushing blood. I passed a huge blood clot in the toilet. I was beside myself thinking that I have definitely had a miscarriage. My husband came and rushed me to the doctors. I had an ultrasound and the doctor confirmed that baby was still in there and fine.  He said that the placenta had separated from the uterus and caused a blood clot.  My cramps were unbearable.  He told me to go home, rest and put my feet up for the rest of the day.  The bleeding and cramps finally subsided after a few hours. I am still shaken up from this awful incident. Has this happened to anyone else?