Suggest Remedies For Prolonged Periods

ive had my period for one month straight. It has been like a normal period: heavy at the start and slowly lighter toward the end. I am 15 and my period usually lasts for 7 days. For the past month, its been like period (one full week) after period...without any stops. I am fairly active, but there are times when I dont get my period for a month or so. What should I do? I am a little worried! Is this normal???