Spotting and Nausea??

I can’t believe I’m posting this but, this past Saturday made two weeks since my period ended. My bf and I had sex the Saturday after my period while I was ovulating. We had sex in between then too, but fast forward to this past Saturday we had sex and I started bleeding followed by spotting until now followed with nausea. I took at test on Tuesday but it came up negative. It is now Thursday and there’s not much spotting but I’m still nauseous. What could this be? Could it be early pregnancy or pms? My period isn’t due to come until next week. I’ve never experienced this before.