positive preg test u/s showed sac but no baby maybe too early to tell.started spotting then 2 days l

Same thing happened to my daughter. She was 8 weeks pregnant, but the sac was that of a 4 or 5 week pregnancy. She was on the verge of loosing it on her own but the Dr. did a D&C instead. Her pregnancy was not a viable one.
Craming and large clots is a sign of miscarraige.
But see your Dr. for a follow up.

I hate to say it, but it sounds an awful lot like my miscarriage. Sure, it's "normal" to spot a little in early pregnancy, but large clots and severe cramping is not good at all. I'm not going to say it's a miscarriage, but you should definitely get to your doctor in case there is something wrong. Good luck!