Chance of pregnancy
is high,if unprotected sexual intercourse is done with ejaculation around ovulation time in regular period. Ovulation occurs approx 14 days before due date.
In your case,you did unprotected sex around safe period (as per calculation your ovulation occurred on 7th Jan if next due date is 21st Jan). So chance of pregnancy is almost nil. It is better to wait for upcoming period and do a urine test for Beta-hcg after 1 wk of missed period to confirm/exclude pregnancy. Check the result and consult with doctor.
It is most probably associated with Pre Menstrual Syndrome (PMS). Do the following things:
1)Avoid salty food/coffee in 2nd half of period,
by yoga/deep breathing exercise
3)Control body wt & Take healthy diet,Drink more water.
4) May need Tab FLUOXETINE
5) Maintain personal hygiene and need proper sleep.
Be well and practice safe sex in future.