Hi, If the slipped IUD has not been shown to have penetrated the cervix, there is no need to worry about significant pelvic injury except that monitoring is needed for a while to look for any infections and after effects. Your other symptoms probably relate to hormonal disturbance caused by the miscarriage and also due to some amount of gastritis; your constipation could be related. Please get a local exam done to rule out organic causes for the pain in the rectum; also get a general check up for your headache and shoulder pain. Hope this helps. Take care.