What Causes Penile Discharge While Urinating?

hello im a 19 year old male i havent been sexually active in.. ever, and ive been noticing something when i urinate its been happening for quite sometime for 3 or more years and i haven't done anything about it afrraid to tell my parents hoping itll stop but it never did, it happens every now and then, maybe once every week or two weeks or even stops for about 3 months and happens again when i urinate, so while im urinating about half way to being finished something white comes out, my pee turns white momentarily. is it prostatic fluid, semen, a yeast infection or an std? what is it? i even sometimes have kidney pain.