Occasionally, people can have some bleeding and cramping while on depo, but it is usually mild and goes away after a few days. If you have been having this discomfort for a month you should talk to your doctor. He/she may need to do an exam to make sure there is nothing else that is causing the discomfort, such as an infection or a cyst
. If indeed there is nothing else, your doctor may want to suggest something to control the spotting, such as a month or two of birth control pills or other possible treatments that should control it. I hope this helps, if you still have any more questions, please feel free to let me know.