What Causes Brown,thick Vaginal Discharge Post Menopause?

I am a 52 year old female. Have been menapausel for over 8 years now. I am experiencing a brown thick discharge from my vagina. It is not an all the time thing that I am aware of but when it does happen I know it I am married but have not had sex in a couple of years. I find myself having to wear a pad it gets so thick at times. Any suggestions? Never mind..thought it was free