What could this be?

I have been bleeding on and off for a little over a week. Some days it’s only about once that I notice when I wipe, and others I’m able to notice more throughout the day. Normally my periods are very heavy with strong cramps and I’m not due for a period yet. The bleeding has varied from light pink spotting when I wipe to dark clumpy brown and I’ve had some but few times of vivid red but only once in a while. I am having light cramping nothing too harsh.