Could Delayed Periods And Subsequent Abnormal Bleeding Indicate A Miscarriage?

hey, i hope you can help, i was 2 weeks late for my pereiod then sudenly i just started bleeding and bleeding im still bleeding and its been 5and a half weeks now my blood is reallly dark brown mostly, and some times dark grey n stringey and i get lots of clotts some times its red but not much, could i be having a threatend misscarrage i have cramps and pain in 1 side of my stomach when i laugh and im really emotional i cant go a day without crying, i did a pregnancy test but it came back negative ..please help me !