Spotting and dizziness but neg test

I had sex aug 16th and i took a pregnancy test last week at exactly 3 weeks and it was negative. This week i started lightly spotting from Wednesday-Friday then it stopped. Typically if i spot i get my period immediately after within the next few hours but it never came and not spotting. Also this week ive been feeling dizzy and lightheaded which is unfamiliar and i tested today and it’s negative. Has anyone experienced this??