Are Abdominal Cramps, Nausea And Dizziness Signs Of Pregnancy?

I started my period on 7/9 last month. My period lasts for 4 days as usual. My husband and I had interiors on 7/23. My period wasn t due until today 7/8 but on the night of 8/1 I started barely spotting. On the third day it got a little heavier with some tissue but still much lighter than a period. Then after a couple of days it went back to light. It will start and stop again. But I am cramping throughout this with extreme nausea, getting dizzy. I took a pregnancy test at lunch yesterday but it was negative. Is it possible it s just too early to test or does this sound like something more serious