What Causes Early And Prolonged Menstruation With Severe Abdominal Cramps?

Hello my cycle was 4 days earlier than what it was supposed to be and my cycle was lighter than normal but lasted 7 days no brown discharge and with bad cramping and nausea but no clots and now that I m off my cycle I am still having bad cramping in my uterus and in my right ovary what could be the cause of this