Ob-Gyn questions? Ask a gynecologist online.
From your description it is evident that you are having with menorrhagia with dysmenorrhoea and anemia.
You are to be treated urgently. It may be due to so many reasons like hormonal imbalance, uterine fibroid,uterine polyp, cervical polyp or fibroid etc.
Gynecological examination and some investigations are required for diagnosis and treatment.