Hi, Thanks for posting in HCM. I understand your concern. Dark brown vaginal discharge what you are experiencing might not be due to pregnancy as your pregnancy tests have come negative. It could be due to various other causes like cervivitis, pelvic inflammatory disease, yeast infection, endometrial bleeding and uterine polyp, which needs to be investigated. Particularly in your case, the cause needs to be known and treated since you are suggesting that your periods are irregular. Kindly consult Gynecologist in this regard for clinical and per speculum examination. Also to confirm the cause, you might be advised to get an ultrasound of abdomen and pelvis done. Accordingly, treatment can be instituted. Hope the information provided would be helpful. All the best.