Hi, I understand your problem. Please do not worry. The depo shots contain progesterone. This hormone also increases in pregnancy producing pregnancy symptoms. This is the reason depo shots also produce pregnancy like symptoms in some women. However, they tend to improve with time. If you have been using depo shots as recommended, than the chances of pregnancy are almost zero. They are very effective in preventing pregnancy. If you are too concerned about pregnancy, get a urine pregnancy test done 3-4 weeks after the date of unprotected sex to rule out pregnancy and ease your stress. My only concern is the frequent urination and backache. This suggests a urine infection. I suggest that you get a urine examination for infection and also a pelvic examination [ cervical and vaginal swab test ] to rule out vaginal or cervical infection. If these are present you will need antibiotics to control them. Hope this satisfies your query. Thanks for using HCM. Feel free to ask any more questions that you may have. Dr Madhuri Bagde Consultant Obstetrician and Gynecologist