Since you have missed three pills in a row, this cycle is no longer protected. You needed additional protection. Also, this irregularity must have resulted in hormone imbalance
and thus caused the bleeding. In the current scenario, exclude pelvic causes through a clinical evaluation and a sonogram. You may go for hormone supplements if the bleeding does not subside. Please see a specialist for further evaluation and management. Please use additional protection for the rest of the cycle. Take care.