There are some physical changes that occur related to the menstrual cycle. The body produces some chemicals that create cramps, headache and fatigue. Some of the hormonal changes affect women and they could have water retention or fluctuations in their moods, explains Dr. Debra Kenward, Obstetrician and Gynecologist with Baptist Health South Florida.
The expert also says, other changes can affect back pain, fatigue, even the bowel movements. A slight of more testosterone creates the acne issues. Changes in dopamine and serotonin can cause more appetite during periods.

Understand more about period pain: https://www.treated.com/understanding-period-pain/