Hi, Thanks for the query. As you are on depo shot, the possibility of pregnancy is less. The possible causes for your spotting are : - Side effects of the depo shot. It can cause intermenstrual spotting, break through bleeding as side effects. -Pelvic inflammatory disease. Chronic pelvic inflammation can present with cervical erosion. And that can lead to spotting, pain abdomen etc. - Post coital tear. Can present with spotting and pain. So, better to consult gynecologist once and get examined. By examination causes like post coital tear, cervical erosion can be ruled out. If your doctor recommends go for ultrasound. Ultrasound will help in ruling out the possibility of pregnancy and also any endometrial abnormality. Then with your doctor s advice you can go for additional dose of hormones to control the spotting. Take care.