Have I Had My First Periods?

Im 12. On Monday when I came home from school, I was SHOCKED to find my discharge was so dark it looked practically black! And I thought it was my period so I put a pad on. On Tuesday, my discharge was still very dark and I noticed there was about more than a pin-prick of blood on the tissue. On wednesday it was still brown but lighter and there was no blood and today the same but the discharge has become a light brown. I have had cramps in my stomach so I thought they were just Period Pains. Have I had my first period or is it getting ready for my period? Iv heard black discharge is the actual Period and blood will come through as you have more, and iv also heard its preparing your body for the period! So Im confused. Iv had clear discharge for about 2 years before Monday. PLEASE HELP!