Here is a website that you may find helpful
http://www.wrongdiagnosis.com/s/simple_kidney_cysts/symptoms.htm
Go to the brain tumor forum and see my thoughts.
I have multiple cysts on my left kidney, and my main symptom was a chronic, nagging, dull ache/pain that seemed to eminate from the kidney itself.
Doctors will tell you that your kidney cannot hurt, as there are no nerve endings there, but don't let the good doctors talk you out of what you're actually feeling.
So cath_e... what exactly ARE your symptoms? They are treatable, laporoscopically, so getting it/them taken care of shouldn't be an issue should that be what you actually have. An MRI is the definitive test for renal cysts, as MRI's are better for imaging soft-tissue. They'll show up on the CT, but not as well as with an MRI.
Talk to me about what you're FEELING...