Irregular period question

So my periods are normally the exact same every month and normally the same day, maybe just a day or two off sometimes. Normally last 4-5 days, I’ll be heavy for about 3 days straight. This month I was about a week late, it only last about a day and a half. I bled kinda heavy half a day and the next day it pretty much fully stopped. Was brown the first day and mine are normally never brown. I took a pregnancy test last week and it was negative, should I test again just to see if that was maybe implantation bleeding? Thoughts??