Confused!

Help me our ladies. This morning I went to the bathroom to pee and saw a streak of blood on the tissue so I thought to myself my period has arrived. Then 3 hours later i went to check if there's was more blood but I was dry. No blood on the Pantiliner or on the tissue 🤔🤔🤔. Some back ground, my period was suppose to start on Monday, so it's 4 days late. I took a pregnancy test on Wednesday and it was negative 👎🏾. So what I confused to what is going on?!?