What Causes White Discharge From Penis After Urinating?

Hi I am a 22 year old Male about 170lbs 6'4" tall and I use methamphetamine by smoking it out of an "oil burner" or glass pipe multiple times a day. Estimated intake is about 2 grams daily sometimes insuffilated intranasally rather than smoked but usually smoked. I noticed recently that urinating feels rather "over-pressurized" or blocked in some sense. I can ease this rather easily by lifting up on my testicles and it causes very little discomfort. However after completing the urination process I still have the mild sensation that I have to continue and when I lift my testicles or massage underneath my testicles I release a thick white odorless discharge much like semen and after the discharge the urination sensation subsides any idea what could be the matter?