My cum has been a brown for a while now and has a odor should i be concerned about this?

Infection? Blood?: Yellow or brown color with odor suggests an infection, probably involving your seminal vesicles (semen collecting sacs). Usually not an STD, but possible if at risk. It could also be blood, espeically if injury to your perineum (between scrotum and anus), e.g. biking, horseback riding, etc. If symptoms continue, see a doctor, preferably a urologist.

Probably okay...: The color and odor of your cum is most likely normal and unique for you. I would not worry about it as long as being free of other symptoms and being known with such pattern as you have observed.