30 is combined OCP and have to take from 1st day of cycle for continuous 21 days and then 7 days off/pill free.You got a withdrawal bleeding like your period within 7 days.
So you have to continue those pill for 21 days on regular basis on scheduled time. If you took irregularly, then unnecessary irregular bleeding may occur due to hormonal
You may do a USG for pelvis if bleeding persists to rule out causes of menorrhagia
. Then consult with your gynecologist.
, take healthy diet.Be well.