It is not normal to experience abdominal pain after sex, especially a week after getting an IUD inserted. The pain may be due to improper positioning of the IUD or its strings. You should see a doctor if you experience persistent pain during or after sex, fever, heavy bleeding, or excessive vaginal discharge. The symptoms should gradually improve and disappear, but it may take a few days or weeks. If you have concerns, it's best to consult with your healthcare provider for further evaluation.