Light bleeding for the past 2 months, swabs came back neg for any infections or STDs. Not pregnant. (Bleeding only at night)brown discharge in the day.

See details. When you say negative pregnancy test I'm going to assume that you had more than one urine test or had a blood test. Since that is negative and the STD testing is negative, you're most likely having dysfunctional cycles meaning you're not ovulating. I would however repeat the STD testing to confirm that they are negative. No test is perfect. Pap test and ultrasound also.