You had unprotected sex, took tab pill o and got your periods OK. I assume that you have irregular diet habits (skipping a meal) and hyper acidity (discomfort after taking food).
You feel the increased pulse rate. The increased heart rate
may be due to hypoglycemia
which increases the heart rate.
Have your diets in regular time, avoiding chilies, and oil fried items. If you feel your pulse rate shoots up take some raw glucose
and observe the result.
If persists do investigations like ECG.