Spotting 1 week before period due

So today I noticed about two small drops of brown discharge in my underwear. When I wiped it was barely on the paper and did have a brown mucus on it. My periods can be a little irregular so of course I don't know what to think. My husband and I did have unprotected sex once right around ovulation, so I'm wondering if it could be my period about to come or maybe implantation bleeding?! I'm having light cramps and was a little naseous today, but my period supposedly isn't due for another week. Don't know what to think! Guess it's a waiting game.