Thank you very much for the useful information Jaye.
Positive ketones in the urine can be due to high protein intake; so its a normal finding if you are consuming high amount of proteins. Similarly, if you are exercising more than usual, again presence of small amount of proteins in the urine is normal.
However, this should not be giving you any symptoms ideally if your body is physiologically producing and excreting proteins/ketones.
At this point, the only test that is going to provide the most useful information is an ultrasound or CT scan of the urinary tract (kidneys/ureter/bladder).
This will rule out the possibility of a stone, or other inflammation in the urinary tract that may also give rise to similar symptoms.
Another remote possibility is of a pinched nerve in the spine (due to disc prolapse or vertebral degeneration) that can give you similar pain in the kidney area and an MRI of the spine is the useful test to diagnose this with certainty.
However, at this point, i would suggest you to keep yourself adequately hydrated, repeat the urine test, and if still abnormal, get CT scan of the renal tract done.
If any abnormality detected, or if deemed necessary, the doctor may order other tests as well such as Renal Function tests, or kidney biopsy.
See your doctor discussing all these details to get further management plan chalked out.
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