My period was supposed to end a week ago but my discharge is still brown and bloody. constant abdomen pain with vomiting but ultrasound/ct normal.

Discharge testing: The brown discharge could just be leftover blood from your period. Since you have vomiting and pelvic pain you are going to have to bee seen by an Obgyn to narrow down the possible causes.

Possibilities: Without a full exam and testing it is difficult to say for sure. I would recommend follow up with a health care provider. Have they tested for infections? Is the discharge related to the other symptoms or independent.? A pelvic ultrasound is more accurate than a Ct scan to look at pelvic organs