last month my period was a dew days late and when it did come, it lasted about 7 days of normal bleeding. not heavy or light. this month, my period was 3-4 days late then i started getting a brownish/black discharge for a couple days. for two days so far I am heavy bleeding with a lot of blood clots. mostly big and I need to change my tampon about every 2-3 hrs. exept for tonight, it seems to be almost gone. could this have been a miscarriage and should I see a doctor?