is this implantation bleeding?

so i’m very worried and confused because my period does not seem normal this time around. i had sex using the pull out method and spermicide on the first day of my fertile window and then the day after i ovulated. it may have still been within the 24 hour window of the egg being alive though. i was experiencing very mild cramping from the day i ovulated until the first day of my period where they began to feel worse. my period arrived on the day it was expected but it has been very light and spotty (heavy with painful cramps on the first day) and the blood seems to be a darker brownish color. it’s now day 4 and i’m only spotting old brown blood when my period usually lasts 5 days with bright red blood the whole time. i took a test this morning and it came back negative, but i feel like maybe it’s too early to test bc i’m still bleeding? should i test again in a week?