I passed tissue with 2 miscarriages at 6wks. Both times I had heavy bleeding and very bad cramping. Sorry for the detail, but in case it helps you to know what the miscarriage tissue was like, it was round and flat, a liitle smaller than the size of my palm, and was whitish color, kind of see through. Good luck. I hope this is not what you are experiencing.
I can't say I've personally been in your situation. Is there any form of bleeding at all, and what did what you pass look like?