It is now day 10 of my period. Why won't it stop?

I’m 47 years old and my periods have always been regular. The first two days I have heavy bleeding, then the next two to three days is very light then over with. This period started as usual but on day 6 I developed a moderate flow. It’s day 10 now and it doesn’t show signs of letting up. It’s still moderate. I have never experienced anything like this.

What’s going on?