Irregular/high heartrate (around 90 to 100) @ week 31

I am having irregular heart rate since last 3 4 days. I am not sure what triggers but all of a sudden i feel like palpitations. Before pregnancy my heart rate was around 65 , in beginning of pregnancy it was 75 around where i felt my heart is pounding but that was for some occasions. At 31 week i am feeling fatigue,headache and pounding of heart, breathlessness. I am not sure but i guess after meal i get this feelings. I talked to my OB she took my blood to check TSH and hemoglobin levels and suggested to go to cardiologist. But my appointment is not until Friday. I am tensed about what could be wrong. Anyone having any experience or any nurse or doctors who can ease my tension. Thank you for reading me out..