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Since you have taken the pills together that would have suddenly raised the hormonal levels in the body and presented as period like bleeding.it is usual if there is change in the pill intake.Kindly avoid unprotected intercourse and start a new pack after the periods.
Regarding the pregnancy if before this episode you have been taking the pills regularly then pregnancy chances are remote.If you notice any unusual symptom consider visiting a Gynaecologist for evaluation.
Take care!