For longer than a year now I have had pain while urinating. I've gone to the doctor and the urine samples come back negative. After I urinate or ejaculate white fluid drips from my penis. The pain while urinating is always different depending on the amount of water I drink. Sometimes the pain feels as if there is something traveling down my penis. What could this be? Occasionally in days when I do not drink enough water I will notice that once I am done urinating there is a drop of urine with a hint of blood dripping from my penis. This, however is not all the time because the multiple urine samples I've had done always come back negative. Help me please