What Causes Heavy Vaginal Bleeding Between Periods?

I am a 43 yr old woman had tubes tied over 20 yrs ago. Had ablasion over 2 yrs ago. I had a period 10 days ago. yesterday I started bleeding bright red blood and now this morning I am bleeding heavier and it is bright red with some orange. very unusual for me. What would cause this? Should I be worried. some cramping on r side of pelvis.