http://womenshealth.gov/publications/our-publications/fact-sheet/premenstrual-syndrome.cfm
Office on Women's Health, U.S. Department of Health and Human Services
Premenstrual syndrome (PMS) is a group of symptoms linked to the menstrual cycle. PMS symptoms occur 1 to 2 weeks before your monthly period starts. An online form is offered to help you track your symptoms and discuss them with your doctor.