Your regular PCP should be able to at least give an educated guess. If he/she feels concerned they can refer you out to a urologist. But as long as its not causing pain or discomfort it might not be serious unless your output (peeing) decreases to much.
Plus it could be a symptom to another condition so its something to think about
Kidney Diseases and Disorders
39 yr young female with,
Chronic Kidney Stones, PKD (Polycystic Kidney Disease), Chronic Kidney Failure, Severe Hypertension, Urological RSD
Also CHF (Congestive Heart Failure) and Sleep Apnea
Hopefully NO MORE........ I think I have it all