I am 54 yrs old and past menopause. For the last 6 months I have been discharging from my viagina. The discharge is sometimes brown and sometimes yellow. I have been check by my gyn and every test that was perform came back negative. The doc said I have 3 fibros, but that they will disappear on their own. This discharge is driving me crazy because it smells really bad and I have to wash my viagina like every 3 hours. The discharge goes toward the back and I keep on developing little pimple on my anus that hurt. I have to wear a tampon so that it won't spread to the back. My panties are stain and when wash, it won't come out. I don't know what is going on. I am not spoing because I have not got my period for 2 yrs already. Do I need to see another gyn or is this common?

You need another gyn opinion. This does sound like some sort of infection.

I was tested for yeast infection and it was negative

A yeast infection is not the only kind of infection that causes these symptoms. There are other illnesses that cause this kind of discharge. Bacterial vaginosis is just one.