Renal fullness

I just had an abdominal ultrasound which revealed right renal pelvic fullness and fullness of both collecting systems. No other findings, bloodwork and urine normal. I had this show up a couple years ago on a CT Scan as well, but this recent report said it is less than what was on that report. At that time I had a large ovarian cyst that has since been removed. What could cause renal fullness if there are no stones, masses or cysts? I have had UTI's in the past, could it be scarring? i do have intermittent pain in the right flank area, but not bad and no trouble urinating.
supposed to go for another CT scan, but not sure if it will show anything more...
I did have a chest x-ray as well, which showed a 5 mm rounded density overlying a mid-thoracic vertebra and i'm having a ct scan of the chest to further evaluate that...so scared....
thank you!