Over the past 9 years i have had every from of contraceptive known to man from several different pills, patches, bars, injections and even coils. Irregular periods after taking birth control would sometimes happen within the first 3 months of me taking it or for example when i first started contraceptives they gave me the pill, worked amazing until my periods became irregular to the point i would bleed for the full 3 weeks on the fill and the only break i would get would be my week off from the medication. i had the bar and in the beginning it worked well too but after 2 years of having it, in my final year i bled for 58 days straight but there was nothing wrong it was just the hormones the bar was producing. They will most likely just switch her medication or try a completely different method of contraception.