I have an iud. and i recently had sex and the day after my stomach was hurting really bad. my period was also way longer than usual. almost a week. what could that mean ?

IUD still in place?: You need to check vaginally for the IUD strings' presence at the cervical opening to be sure that the IUD is still in its' proper place inside the intrauterine cavity. If you are not sure or don't know how, see the GYN MD now who placed the IUD to examine you to be sure that the IUD has not "migrated" outside of the uterus.