Implantation Bleeding?

I’ve been spotting brown for 4 days now, it’s really light. The second day I cramped literally only once and that was it which led me to believe it was my period but my flow never got heavier. The color stayed the same I had a bit of lighter brown and pink. I’ve had no cramping my boobs were bit tender but they feel okay now kinda just like when your periods about to begin but nothing crazy. I have some bloating but for the most part it’s not like when I’m starting my period. I’m supposed to be starting my period in a week but that spotting happened 3 weeks from the first day of my last period. Has anybody had it last that long?