What Causes Bleeding Of Jelly Like Clots During Periods?

hello:.please help!
I missed my period and after 2 weeks i did pregnancy test and its positive ... But then i had little spoting so i got confused and did pregnancy test again and its again positive.... But next day i started bleeding like normal...no pain... but i found some darkred jelly like substance in bleeding.... Its my 4th day oof period what shoud i do???
Is this some thing serious or i m not pregnant anymore???