Brown stringy discharge 12 days before expected period? what causes this? last on and off for 3 daus

Spinnbarkeit: very common midcycle for vaginal and cervix secretions to become very stringy. This is due to the effect of estrogen and is normal. It is also a sign we used to look for ovulation as well. Not to worry. If no other symptoms such as Bad smell to the discharge, bleeding or discomfort or fevers, then not to worry.hope this helps. Best of luck