What Causes Abnormal Vaginal Bleeding With Abdominal Cramps?

Its been 5 days since i had sex for the first time, and my next period is in a month. Now, Ive had a cyst burst in one of my previous periods. Today i started bleeding blood a brownish pink color and it was a light flow and had cramps all day so far..plus the bleeding still. When the cyst burst for the very first time on one of my previous periods, it was a rich bright red and a heavy flow with hardly any cramps..can someone answer me? because i hear that this blood is normally thought of from something else..but i know its also a sign of early pregnancy.