My contraceptive pill caused very light 2 week long bleeding. i havent had a cycle now for 31 days and all pregnancy tests show negative. i feel uncomfortable and like i am gaining weight. any idea as to what it might be?

Irregular period: Irregular periods following introduction of hormonal birth control is very common. It reflects your body's efforts to recalibrate hormones with new levels. It can take up to 3 months to resume normal cycles. Additional side effects include nausea/vomiting, headache, painful menstruation, changes in weight. Talk to your Dr if this bleeding persists.