I tested negative 4 days before my period was due and took another test the day after I missed and it was positive. I too had symptoms early on, before I even tested positive and they've just continuously gotten worse over the past 3 weeks
I started feeling symptoms when I was only 2 weeks pregnant. I would take another test the day after your period is supposed to start and if you get a negative then see a dr.
I don't think you would be experiencing any symptoms this soon if you were. . Sounds like pms and an upset stomach to me..
Also, typical pregnancy symptoms don't start until 6-8 weeks because of the hormone build up. So experiencing them before actually missing a period could have a different cause entirely. I'd wait until 7 days after missed period, test again, and then see Dr if not positive to find what's causing you to feel sick.
You need to wait until you actually miss your period before you test. .. you could get a false negative.
Take another test. If negative and you still have symptoms call a doctor