Need info or advice please reguarding a new type of cancer post Kidney Cancer

I am a 39 yo female who at the age of 28 was diagnoised with Renal Cancer. I have a very hard time "trusting" our imaging process. I was having pain, severe back pain, blood in urine and thought I was having a kidney stone. I had had many, many of these over the years and ALL the same symptoms. After an US, MRI and 2 CT scans my DR's said Nothing is wrong, we can't find ANYTHING wsrong with your Kidneys, My OB/GYN said " This is your Kidneys!!!" He basically had to send me to a different hospital and told me to refuse to leave until somebody listened to me because up to that point all the Dr's said it was GYN related. Finally I was admitted and a wonderful Internist took my case and after many many tests finally did a 3-way CT scan, I had to drink the contrast, have IV contrast and have an enema of contrast and low and behold and huge kidney tumor apeared! It was stage 3 and at the point of breaking out of the capsule. The next few days I stayed in the hospital and they prepared for a radical Nephrectomy. Fast forward a few years later, started having more pain and lots of pelvic bleeding and had to undergo a total hyterectomy by my same WONDERFUL OB/GYN that helped me get my cancer diagnosis. Now , I just had my yearly exam and when he was doing my yearly internal part of the exam he discovered a pelvic mass the size of a small plum. I went for an US and they did a regular one and a vaginal US and found NOTHING!! I am very NOT convinced because of my history and the fact that this has happened before. He wasnt either, he was VERY surprised because he felt it and it hurt and I have nothing in there that could possible confuse things. I am now going for a CT scan but my question for yall is based on my history and previous problems with not finding stuff on CT scans, have anybody ever had these problems, should I insist on another 3-way scan and what are the pros and cons of non-contrast vs contrast. Also what kinds of cancer do I need to look out for since I have already had stage 3 kidney cancer. I would really appriciate any feed back from you guys!! Thank You and God Bless You and many more birthdays for everyone!!!