What Causes Abnormal Menstrual Discharge?

I am a 52 year old female. I have had every symptom of perimenopause since the age of 26. My period comes ever 21 to 28 days and lasts 7 days exactly. I have no cramps or clots during my period. My period is heavy for 3 days stops 1 day and then is light for the remaining days. This is consistant every month for the past year. Just this month, my period ended on 1/17 and to date, I have a brown discharge requiring me to wear a panty liner. Even if the pad is clean, when I wipe there is a brownish pinkish discharge. I am going to make a Dr's appt but would you have an idea of what this could be. I am very worried as I have never had any abnormalities before. Thank you