I had unprotected sex almost 2 weeks ago. I was to start my period on june 21 and didnt sart till june 26. I have been haveing bad cramps. I cant even wear a tampoon because my stomach cramps worse when i wear one. While takeing a shower I passed 3 blood clots that were bigger then a golf ball. I went and bought a pregnanct test and it was negative. I have never had problems with my periods. Is there a chance that I may be haveing a miscarage??? I am also very weak and feel naushious to!!