I'm interested to find out what your OB says as well. I had what I would describe as heavy bleeding at 14 weeks. (Docs might call it moderate. It was several gushes of bright red scary blood). The ER confirmed me and baby were okay, but could not find the source. The next day my OB could not determine the source either. She said, "sometimes it just happens." I'm on pelvic rest until further notice and restricted from exercise. I'm still spotting light brown and hoping to never see that bright red blood again.
Please keep us posted. I know it's scary, but knowing baby is okay should be a relief.