I noticed when i milk my penis, a discharge apears once in the morning, my wife has had a yeast infection, could this be it?

Probably not...: Somehow, fungus has never been reported to cause urethritis. Hence, clear urethral discharge suggests either chlamydia infection or residual liquefied semen after ejaculation. If no symptoms, test urine to assure no chlamydia infection before taking antibiotics; if symptomatic, may be treated empirically and see or tested. Otherwise, leave it alone, wait, and see.