Need advice.

So, on October 13th, I slept with someone. The next day, I bled for 2 days but was rather light.

Anyway, yesterday November 4th, I take a test and it came back negative.. It feels like there is pain where my tubes are, and then excruciating pain in the centre of my stomach, just above my belly button and on the right hand side of lower abdomen.

Can anyone tell me what it could be because I’m losing my mind.

I also had a period on September 29th - October 6th.