anybody had similar experience?

Hi everyone, I had my first miscarriage in 2011, I had some brown spotting and went to the hospital (I wasn't too worried but better to be safe than sorry) I got booked in for an early scan as my hormone levels were too low for me to be 11 weeks pregnant, so I went for the scan and I was told the baby had died at 8 weeks 4 days. I decided to go with a natural miscarriage which began to happen 4 days later. I was sitting on the toilet with blood and clots about the size of my whole hand (sorry for tmi) pouring from me, as I'd never had a miscarriage I thought this was normal until I went unconscious when my husband rang an ambulance, after 2 nights in hospital (slipping in and out of consciousness and still heavily bleeding) they tried to unblock my cervix but nothing was working so they finally decided to give me a d&c and a blood transfusion. My second miscarriage was on 29th January this year, which if my last pregnancy had gone to full term would have been my babys first birthday. The same heavy bleeding and clotting happened again, I was just standing at a cash machine when it suddenly started to gush out of me, my husband and I got an ambulance to hospital where I slipped unconscious again and woke up in resus as my heart rate dropped dangerously low. The doctor managed to stop the bleeding by unblocking my cervix this time, but I just can't understand why this has happened twice???? Has anybody else had a miscarriage like this and did you get an explanation????