I'm Going On 16 Days Of A Never Ending Period.

I'm going on 16 days of a never ending period. I usually have very irregular menstrual cycles, sometimes twice in one month. This is very different though, the blood seems to be slightly lighter in color and a lot of blood clots. It fluctuates between being very heavy and somewhat lighter. Currently it seems to be getting heavier, especially when I use the restroom. If my doctor can't get me in immediately is this something that I should make an ER visit for?