I Am Very Concerned I Had A Heavy Menstrual On

I am very concerned I had a heavy menstrual on December 25th that lasted 4 days then one January 6th very heavy for 3 days and now it's January 23 and I'm having another heavy one is this normal I'm not stressed but I have been having tenderness in my belly I only have one tube and one ovary do I need to go to doc also my menstruals are very dark in color