What Causes Severe Pain In Lower Abdomen Along With Heavy Bleeding?

the other day I was experiencing a very strong pain in my lower uterus and in my back I have been bleeding heavily for the last 24 hours with extreme pain this afternoon I went to the bathroom and I felt a pressure fall out of me and I looked in the toilet and there was a mass of some sort I ve seen lots of clots before but I ve never seen something like this its not squishy like a clock is its more solid and it s got more like nerves kind of v ines do it trying to see if that is a miscarriage and what should I do in that situation