Does Heavy Menstrual Bleeding Indicate Sign Of Menopause?

I am 51 years old and am having irregular periods. This current period is flowing extremely heavy and I m wondering if this is the onset of menopause and how can I possibly discharge so much blood....heavy bleeding for five days straight? Doesn t the uterus hold just so much blood prior to a pregnancy. Where s all this blood coming from? Just a bit of information. I had very regular periods 28-30 days throughout my years of menstruating. Please help! I m going through pads every few hours.