Suggest Treatment For Irregular Menstrual Periods

my 11 year old started her period one month before her 10th birthday in Dec of 2009. her dad died very unexpectedly less than a month later. she's experienced irregular periods which is expected, but for the last 2 o r 3 months they've been happening every 2 wks and lasting approx 7 days. she finished a period a week ago and today started another. advice?