I have been lightheaded when walking and feeling fatigued and even falling asleep sometimes and occasional chills and had a neg pregnancy test?

R/o anemia,hypothyro: Though early pregnancy can cause above symptoms, anemia, hypothyroidism can cause early pregnancy can cause similar symptoms , hence repeat the pregnancy test if suspicious of pregnancy after another 2-3 wks if still you don;t get your periods and anemia/low thyroid fn are ruled upt with blood investigations. Get an appointment with your pcp.