First of all, do a home pregnancy
test with urine for beta HCG
if you missed period for more than 7 days. Check result and consult with your doctor.
Pregnancy is possible only, if unprotected sexual intercourse is done with ejaculation around ovulation time in regular period.
Other close possibility is Pre Menstrual Syndrome (PMS) if pregnancy is ruled out. Then you should follow certain measures like
1) avoid salty food/ coffee in 2nd half of period,
2) Avoid stress
by yoga/deep breathing,
3) Control body wt by regular physical exercise
4) Take healthy diet and drink lots of water
5) wear tight breast support for breast discomfort and take PRIMOSA
6) use some medication like anti spasmodic for cramp or Omeprazole
7) maintain personal hygiene and need proper sleep.
Be well and take care.