If symptoms including mood swings, fatigue, and anxiety do not follow monthly cycle, it could be depression, thyroid imbalance, or even Premenstrual Dysphoric Disorder (PMDD). Dr Mitali Rathod, Obstetrician and Gynaecologist, says, “Very severe PMS symptoms could be PMDD, which can include depression, anger, or anxiety." If this is happening, speak with health expert, she suggests.