PMS or Premenstrual Syndrome is a condition experienced by people typically 7-10 day before their periods. Before menstruation the body goes through a hormonal changes which leads to certain symptoms that the body shows.
Some of the symptoms of PMS include bloated tummy, abdominal cramps, tender breasts, change in appetite, headache, breakouts, change in bowel movement, weight gain, mood swings.
Additionally, there are emotional and behavioral changes that the body also goes through along with physical changes.
Sources:
https://www.healthline.com/health/premenstrual-syndrome
https://www.mayoclinic.org/diseases-conditions/premenstrual-syndrome/symptoms-causes/syc-20376780