Confused by my results- Please help!
 

So I had gone into the ER with lower abdominal pain and the doctor ordered a CT. He came back in and told me they found nothing with the abdomen but that I have a 2cm mass on my left breast. He said he would seriously suggest that I go get a mammogram, but my doctor refused to give me a mammogram (im 24 years old)
She instead gave me an ultrasound order. I went today and they could not find anything but the radiologist had said the CT showed a definate "something" on it.
So I guess my question is...Do ultrasounds always show cysts or what are they meant to detect? Im scared because I have serious tenderness and the fact that the CT picked it up but not the US is worrying me!
Please help....Should I request more diagnostic testing or leave it alone?