My Mother Has Stage 4 Uterine Cancer. It Has Spread

My mother has stage 4 uterine cancer. It has spread to colon and neck. She has diarrhea for past 3 days and today her stool is black. Her dr appt is tomorrow but do you think it has spread to her stomach bc she says it hurts. I want to be prepared for what the dr might say. She was diagnosed in March and dr said its aggressive.