Hello, With depo shot, pregnancy rate is quite low- 0.3%. Above features are mostly associated with withdrawal effects of depo shot in association with hormonal imbalance and mental stress. Pulled out method has high failure rate in the absence of depo shot and you have to rule out possible conception by undergoing one home pregnancy test. Blood test is more confirmatory. Brown discharge may indicate implantation bleeding or early sign of miscarriage. Take balanced diet, drink more water, avoid stress and maintain genital hygiene. Kindly consult with gynecologist after doing initial tests. Practice safe sex in future. Good luck.