I wrote an article for ProjectKnow on Premenstrual Dysphoric Disorder (PDD), and everything you should know about it... 

"Premenstrual dysphoric disorder (PDD) is a severe premenstrual disorder that is defined by psychiatric or somatic symptoms that develop during the late luteal phase (after ovulation) of the menstrual cycle (or 7 to 10 days before menstruation) and end after menstruation begins.1 While it may share some symptoms with Premenstrual Syndrome (PMS), it causes significantly more distress that negatively affects a woman’s mental health and is officially classified as a mental health disorder, whereas PMS is not. Some symptoms common to PDD and PMS might include..."