16cm X 12cm Mass

In 2006 I underwent a laparoscopy for a 4cm X 7cm complex pelvic mass and was told that there was no mass only complex scar tissue and something that I was probably born with. I began experiencing LLQ pain and went to my physician and was send for an ultrasound on 04/17/09 which revealed a 16cm x 12cm mass in the right hemipelvis between the abdominal wall and bladder, that they believed to be ovarian cancer at the time because neither ovary was could be seen. After laparoscopy number two, I was told that I had endometriosis and a left ovarian cyst. The mass was not removed because the GYN oncologist said it was not in his scope of practice and referred me to a urologist for what he believed to be a urachal cyst. I saw the urologist last Wed. who, after getting a second CT scan and doing a cystoscopy said that he could not help me because it was not a urachal cyst and it was not urologic, he thinks maybe sarcoma and is sending me to a Oncology surgeon on 06/15/09. Meanwhile this "mass" is growing and causing increasing episodes of pain. Has anyone had a similar experience with such difficulty diagnosing. And any ideas as to what this might be?