i've been having irregular periods for a while. when they were heavy i had large clots, and i changed my tampon every 2 hours. then i would go through a month of spotting. the doctor has taken tests on me and found nothing wrong so they say i just have d.u.b = dysfunctional uterine bleeding by hormonal imbalance. so the only thing they can do is try to regulate my period. and i m so frustrated b/c after surgery hysteroscopy and d&c i still have irregular periods.
so your doctor maybe right. tell your sister to have patients and keep going to the doctors. if you dont like what he says try to get a second opinion.