9dpo -12dpo bleeding

My period is never early, sometimes a day rarely 2, but this time it came 6 days early. I was immediately alarmed. I started spotting 9dpo, it was heavy and continued until today (12dpo) I’ve had light spotting. My boobs were tender and feel bigger, but don’t seem seem to hurt today. I also have been tired and have had head aches. My sister in law says this happened to her, she thought it was an early, lighter period but it was actually her first symptom of pregnancy.

I know symptom checking isn’t good, but I can’t help but wonder why my period came so early? Could it be because of a failed implantation, implantation, or just a change in hormones that caused a early period.

Let me know if this has happened to anyone and why!! Thank you

Update: took a test same day it was negative!