Had a week of light spotting, up to the day my cycle came which was a day after my start date and i bled heavy for 9 days clots and cramps. why?

Vaginal bleed: If are/have been sexually active Important to urgently know your pregnancy status. Take a test now and if positive seek urgent attention to exclude miscarriage or other pregnancy related problem. Otherwise may be infection or menorrhagia (heavy period) and there may be a variety of medical reasons for and best to see a doctor for an examination and consideration of tests.

Irregular bldg.: Your symptoms may be secondary a "miscarriage", or in some cases, a more serious medical problem of a present pregnancy other than in the uterus. See your healthcare provider for a serum HCG test to rule out pregnancy, and then your GYN for an exam to determine the cause ( "fibroids. early miscarriage, etc.)