Most often it is related to urinary
tract problems like kidney stones, inflammation of
urinary tract, infections of the
urinary tract, prostate enlargement, renal vein thrombosis, certain kidney tumors and polycystic kidney disease, blood coagulation disorders and anticoagulants.
It does not seem to be related to testicular infections causing orchitis.
I hope it helps. Take care and please do keep us posted on how you are doing. Kind regards.