Weird question

Lexus

So Im supposed to be on my period (about 1 day late) and I thought I started on Thursday because I saw some blood when I went to the bathroom but it was just brown discharge and since then every pad I’ve worn has nothing on it.

When I looked it up I guess brown discharge can either be old blood shedding or implantation bleeding.

Should I take a pregnancy test? I took one on Monday because I was curious and it was negative... could 4 days change that?