Hello, You have taken depo shots and thereafter you have been getting heavy bleeding., you are nauseous, light headed and uncomfortable. The hormone from the birth control shot stays in your body for at least three months and hence causes side effects like bleeding, may continue for several weeks. Irregular bleeding, heavy bleeding, breakthrough bleeding, lighter periods or no periods are common side effect of the birth control shot. For many women, side effect often goes away over time. In each shot, Depo-Provera delivers high dosage of progestin. With each injection, the body needs time to adjust with the level of hormones. The first few months with the birth control shot causes side effects that you are experiencing. After your third or fourth injection, the body gets accustomed to respond to the increased level of hormone and slowly the side effects go away. In case the bleeding is very heavy, get clinically examined by a gynecologist, to rule out any pathology associated with symptoms so that it can be treated at the earliest. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician