Females have one cycle that is ovarian with period blood and the other is uterian with the lining that holds the blood in place. Prostaglandins, the chemicals that tell your body to shed the uterine lining, happens totally independent from period blood. Your discharge is clear and sticky, the lining is white stringy mucous. This is when you will see the brown old blood.
Premenstrual syndrome (PMS) refers to physical and emotional symptoms that occur in the one to two weeks before a woman's period. Symptoms often vary between women and resolve around the start of bleeding. Common symptoms include headache, acne, tender breasts, bloating, clear discharge, feeling tired, irritability, and mood changes. Often symptoms are present for around six days. A woman's pattern of symptoms may change over time. Symptoms do not occur during pregnancy or following menopause.