Threatened Miscarriage

Had anyone had one of these before.?! I'm about 6-7 weeks. I started bleeding yesterday around 8pm, went to the ER was there for 4 hours and all they said was to call my OB this morning that i was having what they called a threatened miscarriage. They did bloodwork and everything was normal, he said my HCG level was in the 7,000s and did a pelvic exam and said my cervix was closed. So thats all good news but where is this bleding coming from.?!?! I've called and left a message....the wait to get a call is killing me. I just wanna know what is going on. Not knowing is by far the absolute worse feeling in the pit of my stomach. I've prayed all night, no bleeding today so I'm hoping for some positive news. I've Googled so many things I'm losing my sanity.