Hi all sorry if TMI

I had on and off cramps today in my lower stomach which felt like period pains but I'm not due on for 3 days, I come on tonight but it's a very light bleeding I'm really confused on what it could be and could do with some advise please.

Done a test Sunday and it come bk BFN.

I really don't know what it can be, if it is implantation or not. I have never come on early and when I do come on for the first few days in heavy.

Advise please