This is an interesting situation.If this problem is only for the last 3 months then we have to look into the problem with little extra care. Trace ketones and normal blood sugar signifies that he does not have diabetes
. This problem may occur if he has a stone somewhere in his urinary tract
or a bladder inflammation
.This can be overcome by giving him some Alkasol solution with water for few days. Water intake should be increased adequately. If the problem persists a through investigation of his urinary system
should be done. Wishing you the best.Have a nice day.