The Day Before Halloween, I Thought I Started My Period

The day before Halloween, I thought I started my period 3 weeks early. I only spotted that first day, the next day nothing. The day after I began spotting again, then Saturday morning, I began gushing blood. I've been having excruciating, cramp style pains. Reminds me of contractions. To stand after sitting, to sit after standing, both nearly unbearable. Walking is a battle. The pain in my abdomen is so bad, it keeps me doubled over. I'm still losing a lot of blood, I'm scared